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Expression of long noncoding RNAs in peripheral blood mononuclear cells of patients with type 1 diabetes mellitus: potential biomarkers for disease onset.

OBJECTIVE: Long non-coding RNAs (lncRNAs) do not encode proteins and are transcripts longer than 200 nucleotides. The precise involvement of lncRNAs in type 1 diabetes mellitus (T1DM) pathogenesis remains unclear. Therefore, this study aimed to analyze the expressions of five lncRNAs in peripheral blood mononuclear cells of individuals with T1DM and without DM. MATERIALS AND METHODS: This study comprised 27 patients with T1DM (cases) and 13 individuals without DM (controls). The case group was divided into two subgroups based on T1DM duration: < 5 years of diagnosis group and long-term diabetes group (&#x2265;5 years). LncRNA expression was evaluated by qPCR. RESULTS: MALAT1 and TUG1 were upregulated in patients within the first five years of diagnosis of T1DM compared to the other groups. MEG3 was upregulated in the case group of < 5 years of diagnosis compared to controls. TUG1 and MALAT1 levels were negatively correlated with the duration of T1DM, while TUG1 and MEG3 were positively correlated with glycated hemoglobin levels. Bioinformatics analysis revealed that MALAT1, MEG3, and TUG1 regulate and interact with protein-codifying genes and microRNAs involved in T1DM-related pathways. CONCLUSION: Our study revealed MALAT1, MEG3, and TUG1 upregulation in patients within the first five years of diagnosis of T1DM.

Humans

A Comparative Analysis of the Methylation Status of Non-Coding RNA Promoters in Fibroid and Matched Myometrium.

Uterine fibroids exhibit dysregulated expression of non-coding RNAs (ncRNAs), although the underlying mechanisms remain incompletely understood. We investigated promoter DNA methylation and its relationship with ncRNA expression in fibroids. Genomic DNA from eight paired fibroid and matched myometrial tissues was analyzed using MeDIP-chip to identify differentially methylated ncRNA promoters. Selected candidates were validated by methylation-specific PCR (MSP) in 16 paired samples, and transcript expression was assessed by qRT-PCR in 68-94 paired specimens. MeDIP-chip identified 538 lncRNAs and 61 miRNAs with differential promoter methylation, including 300 hypermethylated and 238 hypomethylated lncRNAs and 47 hypermethylated and 14 hypomethylated miRNAs. Promoter methylation was not significantly correlated with transcript expression (r = -0.1224). MSP confirmed hypermethylation of LINC-PINT and MIR9-3 and hypomethylation of WT1-AS and TTLL10-AS1. Correspondingly, LINC-PINT and MIR9-3 expression was decreased, whereas WT1-AS and TTLL10-AS1 expression was increased in fibroids. However, LINC-PINT and TTLL10-AS1 methylation did not fully correspond with MeDIP-chip findings. These results reveal widespread ncRNA promoter methylation alterations in uterine fibroids but demonstrate that genome-wide methylation does not consistently predict transcript expression, highlighting the complexity of ncRNA epigenetic regulation and the importance of locus-specific validation.

Humans

Targeting ncRNA control networks with engineered exosomes to overcome therapy resistance in thyroid cancer.

Papillary thyroid cancer (PTC) is the most prevalent endocrine malignancy, accounting for over 90% of thyroid cancers. While differentiated thyroid cancers (DTCs) typically have favorable outcomes, a significant subset progresses to radioactive iodine-refractory (RAIR) disease, characterized by impaired iodine uptake and a 10-year survival rate below 10%. Genetic alterations and dysregulated signaling pathways underlie this transition. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs), play critical regulatory roles in tumor biology and may be transported via exosomes, facilitating intercellular communication and contributing to RAIR-PTC. This systematic review, conducted according to PRISMA 2020 guidelines, evaluated the role of exosomal ncRNAs in RAIR-PTC. A comprehensive search of PubMed, PubMed Central, and Google Scholar identified studies published within the past 15 years in English. Following stringent quality appraisal, studies with a non-bias score above 40% were included. Of 961 identified publications, 96 high-quality studies met inclusion criteria. Evidence indicates that therapy resistance in RAIR-PTC is driven by convergent ncRNA regulatory networks that suppress sodium-iodide symporter (NIS) expression and activate oncogenic pathways, most notably MAPK, PI3K/AKT/mTOR, and Wnt/&#x3b2;-catenin signaling. Multiple ncRNAs converge on key regulatory nodes, forming redundant circuits that sustain dedifferentiation, metabolic adaptation, and impaired iodide transport. Several consistently dysregulated ncRNAs directly or indirectly regulate NIS expression and trafficking, highlighting actionable targets. Exosomes emerge as biologically compatible, programmable delivery vehicles capable of transporting therapeutic ncRNA payloads independent of endogenous packaging mechanisms. These findings support a precision therapeutic paradigm in which engineered exosomes reprogram ncRNA networks to restore iodine-handling pathways and overcome therapy resistance in RAIR-PTC.

Humans

Characterization of double-stranded RNA genetic elements associated with biological control of chestnut blight: organization of terminal domains and identification of gene products.

We have determined the organization within the terminal domains of the major large double-stranded RNA genetic elements associated with the hypovirulent strain EP713 of the chestnut blight pathogen Cryphonectria (Endothia) parasitica. Only the polyadenylated strand contained long open reading frames. Furthermore, only RNA of the same polarity as the polyadenylated strand was detectable in a single-stranded form, indicating that the polyadenylated strand is the coding or plus strand. The organization of the 5'-proximal portion of the plus strand consisted of a 495 nucleotide non-coding leader sequence followed by two overlapping open reading frames. The first, ORF1, extended 957 nucleotides while the second, ORF2, began 68 nucleotides upstream of the ORF1 termination codon and extended at least 1412 nucleotides. No open reading frames of significant size were detected within 0.8 kb of the poly(A) tail. In vitro translation of synthetic transcripts containing ORF1 yielded a polypeptide of Mr 29 kd. The ORF1 product was also detected in lysates of the hypovirulent strain but was absent in lysates of the isogenic virulent strain. It represents the first protein to be identified as a gene product encoded by a hypovirulence-associated double-stranded RNA genetic element.

Amino Acid Sequence

The complete and symmetric transcription of the main non coding region of rat mitochondrial genome: in vivo mapping of heavy and light transcripts.

The experiments here reported demonstrate that the main non-coding region of rat mitochondrial DNA is symmetrically transcribed. We have identified stable heavy and light transcripts, whose pattern is rather complex, in the D-loop region of rat mitochondrial DNA. Their relative concentrations have been determined. We detected heavy transcripts which encompass the whole D-loop and more abundant heavy RNA species which we interpreted as transcripts terminating downstream of the 3' end of the last coded gene (Thr-tRNA). The processed heavy RNA species contain polyA, suggesting a strict association between cleavage and polyadenylation. The pattern of light transcripts shows a long RNA, which, starting from the light strand promoter, covers the whole segment, and shorter RNA species which seems to be actively processed at the level of the conserved sequence boxes, probably acting as primers. The symmetric transcription of the D-loop containing region of rat mitochondrial DNA, and in particular the presence of stable transcripts complementary to the putative RNA primers, suggest that mechanisms mediated by interaction between complementary transcripts (antisense RNAs) might play a role in the regulation of mitochondrial DNA replication and expression.

Amino Acid Sequence

mRNA for the three human alcohol dehydrogenase subunits: size heterogeneity and developmental changes.

Human alcohol dehydrogenase consists of three types of subunits (alpha, beta, and gamma) which are governed by three separate loci. mRNA components for the three subunits were examined by Northern blot hybridization, using a common cDNA probe and specific oligonucleotide probes. A marked size heterogeneity of beta mRNA, ranging from 1.6 kb to 5.2 kb (of which the 2.4-kb and 3.5-kb were major), was observed in the adult liver. The mRNA for the gamma subunit was homogeneous (about 1.6 kb), and that for the alpha subunit contained a major 1.6-kb and a minor 4.3-kb component. The amount of mRNA was much lower (approximately 10% of adult) and the mRNA was less heterogeneous in the infant liver; i.e., an alpha mRNA (1.6 kb) and two beta mRNAs (a major 1.6 kb and a minor 3.5 kb), and no detectable gamma mRNA. The short beta mRNA, with 1.6 kb, could not be hybridized with a non-coding cDNA fragment that originated from the 3'-end of the 2.6 kb beta cDNA. The observed multiple ADH mRNAs, with a common coding region and different 3'-untranslated regions, are generated by utilization of multiple polyadenylation signals. The selection of polyadenylation signals and the rate of transcription of the three ADH loci are developmentally regulated. The 4.3-kb-long mRNA, which was hybridized with both a- and beta-specific probes, could be related to the previously cloned "fused beta-alpha" cDNA.

Adult

Characterization of cDNA clones coding for muscle tropomyosin of the nematode Trichostrongylus colubriformis.

The host-protective antigen from detergent-solubilised extracts of the sheep intestinal helminth Trichostrongylus colubriformis has been identified as tropomyosin. Complementary DNA clones coding for T. colubriformis muscle tropomyosin have been isolated and characterised as the first step in obtaining recombinant protein to carry out more extensive vaccination trials. The clones represent an mRNA of 1544 bases, including a relatively long 5' untranslated sequence of 307 bases and a 3' non-coding region of 344 bases. The mRNA codes for a highly alpha-helical protein of 284 residues with a molecular weight of 33,000; characteristics typically observed for the muscle tropomyosins of higher organisms. The T. colubriformis protein has 58% sequence identity with rabbit and Drosophila melanogaster muscle tropomyosins, and the differences in the protein sequence are randomly distributed throughout the molecule. There is complete identity between the three sequences for the N-terminal 9 residues, the region believed to be essential for the polymerisation of tropomyosin molecules and for binding to actin and troponin.

Amino Acid Sequence

Secondary structure at the 3' terminal region of RNA coliphages: comparison with tRNA.

Secondary structure models for the 3' non-coding region of the four groups of coliphage RNA are proposed based on comparative sequence analysis and on previously published data on the sensitivity of nucleotides in MS2 RNA to chemical modification and enzymes. We report the following observations. (1) In contrast to the coding regions, the structure at the 3' terminus is characterized by stable regular helices. We note the occurrence of the loop sequences 5'-GUUCGC and 5'-CGAAAG, that are reported to confer exceptional stability to stem structures. These features are probably present to promote the segregation of mother and daughter strands during replication. (2) Comparison of homologous helices indicates that only those base pair substitutions are allowed that maintain the thermodynamic stability. (3) We have compared the structure of phage RNA with tRNA. Overall similarity is low, but one common element may exist. It is a quasi-continuous helix of 12 basepairs that could be the equivalent of the 12 basepair long coaxially stacked helix, formed by the T psi C arm and the aminoacyl acceptor arm in tRNA. As in tRNA, this structure element starts after the fourth nucleotide from the 3' end. (4) Phage RNA contains a large variable region of about 35 nucleotides bulging out from the quasi-continuous helix. We speculate that the variable loop in present-day tRNA could be the remnant of the variable region found in phage RNA. The variable region contains overlapping binding sites for the replicase enzyme and the maturation protein. This common binding site may serve as a switch from replication to packaging.

Anticodon

Genome-wide association study reveals two novel genetic loci associated with chronic lung allograft dysfunction.

BACKGROUND: Chronic lung allograft dysfunction (CLAD) leads to declining respiratory function and high mortality, representing the main barrier to long-term survival in lung transplantation (LT). We performed the first genome-wide association study (GWAS) investigating donor's and recipient's genetic factors associated with CLAD. METHOD: We genotyped 392 donor-recipient pairs from the multicentric Cohort in Lung Transplantation. We tested 4.5 million SNPs for association with CLAD using multivariable logistic regression models corrected for age, sex, initial disease and genetic ancestry. Three levels of explanatory variables were separately considered to conduct GWAS: donors-only, recipients-only, and donor-recipient mismatches. We also ran HLA-centric analyses using the same models. RESULTS: Our analysis confirmed the deleterious impact of HLA allelic and epitopic mismatches on CLAD risk, mostly driven by class I HLA (p=0.004). No significant associations with CLAD were found for donors' genotypes or donor-recipient non-HLA mismatches. We highlighted two independent recipient's loci associated with CLAD, including one protective signal (0.39 in CLAD vs 0.66 in non-CLAD recipients, p-value=5.05&#xd7;10-7, q-value=0.017, OR=0.35) encompassing the PLXDC2 gene, and one risk signal (0.66 in CLAD vs 0.38 in non-CLAD recipients, p-value=9.86&#xd7;10-7, q-value=0.017, OR=2.83) encompassing the ZNF518A/BLNK genes. These non-coding SNPs are putative regulatory variants of gene expression. Importantly, our single-cell RNA-sequencing showed a down-regulation of PLXDC2 in fibroblasts and lung epithelium in CLAD vs healthy controls. CONCLUSION: This first LT GWAS revealed two candidate loci from the recipient's genome, both biologically relevant for CLAD pathogenesis. Our study calls for larger LT genomic initiatives to increase power for signal discovery.

Humans

Micropeptides encoded by lncRNAs associated with cancer progression reveal novel immunogenic epitopes.

MOTIVATION: Long non-coding RNAs (lncRNAs) regulate gene expression, chromatin organization, and cellular signaling. Recent studies indicate that &#x223c;20% of the &#x223c;36&#x2009;000 human lncRNA genes harbor small open reading frames (sORFs) capable of producing micropeptides (MPs), whose functions remain largely unknown. Whether these peptides contribute to the cancer immunopeptidome is largely unexplored. RESULTS: We systematically analyzed lncRNAs with strong experimental and computational evidence of MP-encoding potential (&#x223c;13% of the initial MP collection). Using The Cancer Genome Atlas (TCGA), we identified 2606 high-confidence lncRNA-derived MPs encoded by 647 genes across 16 cancer types. We then focused on 501 MPs from 124 lncRNA genes whose expression changes significantly across tumor stages and metastatic transitions, representing cancer transitional lncRNAs (Tr-lncRNAs). Dipeptide composition and conservation analyses showed that these MPs differ from a size-matched human coding proteome, supporting their potential as neoantigens. All possible 9-mer peptides were evaluated for predicted binding to prevalent European HLA class I alleles. Approximately 60% of Tr-lncRNA genes and 184 (37%) of derived peptides exhibited strong predicted HLA binding. Peptides from XIST, PCAT7, PVT1, HAND2-AS1 showed broad HLA coverage. Notably, TTN-AS1, encoded an MP (79 aa) generated 33 predicted distinct epitopes spanning all 27 HLA alleles. Our analysis identifies lncRNA-derived MPs as a previously underexplored source of potential cancer neoantigens, highlighting their promise as biomarkers and targets for immunotherapy. AVAILABILITY: Data, code and supplementary materials are available in https://doi.org/10.5281/zenodo.20167452 and GitHub: https://github.com/stavzok1/lncrna_peptide_analysis.

Humans

Abundant 5 kb RNA of human cytomegalovirus without a major translational reading frame.

Although all herpesviruses are similar in their temporal regulation of gene expression, the organization of the immediate early (IE) genes varies markedly between the different members of the group. Most of the IE transcripts of human cytomegalovirus originate from a restricted region within the long unique segment of its linear dsDNA genome of 235 kb. One of the predominant transcripts from the IE region is a 5 kb RNA. Northern blot analyses revealed that this class of RNA is continuously present in infected cells. It was detected at high levels in IE and late RNA preparations, and in low amounts in early RNA preparations. It was not confined to the poly(A)+ fraction upon oligo(dT) selection, but also appeared in similar amounts in poly(A)- fractions. Fine mapping of this transcript was done by nuclease protection and primer extension. The RNA appeared to be unspliced, and no signals such as TATA or CCAAT, known to be important elements in eukaryotic RNA polymerase II promoters, were found close to the 5' end. Sequence analysis revealed multiple stop codons throughout the AT-rich potential coding region. Since no splicing was found to occur, the largest protein deduced from the DNA sequence would be of not more than 12,000 Mr. However, a computer program designed to detect protein-coding DNA sequences by codon usage did not reveal significant evidence for a protein encoded in this region. Therefore this RNA is likely to represent an unprecedented case of a large non-coding transcript present in cells that are lytically infected by an animal virus.

Base Sequence

Nucleotide sequence and evolutionary relationships of cucumber mosaic virus (CMV) strains: CMV RNA 1.

The nucleotide sequence of RNA 1 of the Fny strain (Subgroup I) of cucumber mosaic virus (CMV) was determined and compared at both the nucleic acid and protein levels with the corresponding sequence of RNA 1 of the Q strain (Subgroup II) of CMV. Fny-CMV RNA 1 consisted of 3357 nucleotides and contained a single long open reading frame (ORF) of 2979 nucleotides, whereas Q-CMV RNA 1 consists of 3389 nucleotides and contains a single ORF of 2973 nucleotides. The levels of sequence homology between the two RNAs were 76% at the nucleotide level and 85% at the protein level. These homologies were distributed widely over the molecules, with 45% of the non-conservative differences in amino acid sequence located between amino acids 503 and 705, and another 15% of the differences located between amino acids 224 and 298. While the C-terminal 141 amino acids contain more basic than acidic amino acids, the region of greatest amino acid sequence heterogeneity, amino acids 503 to 600, contained a preponderance of acidic amino acids in the putative translation products of RNAs 1 of both Q-CMV and Fny-CMV. The last 180 nucleotides of the 3'-terminal non-coding region of Fny-CMV RNAs 1 and 2 were 96% homologous, whereas the sequence homology between Fny-CMV RNA 1 and Q-CMV RNA 1 was 64% in this region. Furthermore, the tRNA-like secondary structures formed by the 3'-terminal non-coding regions of Fny-CMV RNAs 1 and 2 were virtually identical. By contrast, there was only 84% sequence homology between the 5'-terminal non-coding regions of these two RNAs and 81% sequence homology between the 5'-terminal non-coding regions of Q-CMV RNA 1 and Fny-CMV RNA 1. The non-equivalent divergence in the non-coding regions of these RNAs, as well as possible functions for the translation product of RNA 1, are discussed.

Amino Acid Sequence

The complete nucleotide sequence of swine vesicular disease virus.

The complete nucleotide sequence of the genome of the enterovirus swine vesicular disease virus (SVDV; H/3 '76) isolated from a healthy pig has been determined using molecular cloning and DNA sequencing techniques. The RNA genome was 7400 nucleotides long, excluding the poly(A) tract, and appeared to encode a single polyprotein of 2185 amino acids. The predicted amino acid sequence of the polyprotein showed close homology (around 90%) to that of the previously sequenced coxsackieviruses B1, B3 and B4, and also showed homology (around 60%) to that of poliovirus. This homology allows us to predict the possible cleavage sites of the polyprotein and to identify other features of structural and functional significance, which seem to be important to the biological integrity of the virus. A detailed analysis of homology between SVDV and coxsackieviruses shows that non-structural proteins are highly conserved whereas the structural proteins are less well conserved. The 5' and 3' non-coding regions are also conserved, although there are several divergent nucleotide stretches. These stretches may differentiate SVDV from coxsackieviruses.

Amino Acid Sequence

The nucleotide sequence of satellite RNA in grapevine fanleaf virus, strain F13.

The nucleotide sequence of cDNA copies of grapevine fanleaf virus (strain F13) satellite RNA has been determined. The primary structure obtained was 1114 nucleotides in length, excluding the poly(A) tail, and contained only one long open reading frame encoding a 341 residue, highly hydrophilic polypeptide of Mr37275. The coding sequence was bordered by a leader of 14 nucleotides and a 3'-terminal non-coding region of 74 nucleotides. No homology has been found with small satellite RNAs associated with other nepoviruses. Two limited homologies of eight nucleotides have been detected between the satellite RNA in grapevine fanleaf virus and those in tomato black ring virus, and a consensus sequence U.G/UGAAAAU/AU/AU/A at the 5' end of nepovirus RNAs is reported. A less extended consensus exists in this region in comovirus and picornavirus RNA.

Amino Acid Sequence

Molecular cloning, sequencing and expression in Escherichia coli of the bean yellow mosaic virus coat protein gene.

The sequence of 1015 nucleotides from the 3' poly(A) tract of the potyvirus bean yellow mosaic virus (BYMV) RNA has been determined from two cDNA clones. This sequence contained a single long open reading frame (ORF) starting upstream of the cloned region. The ORF was expressed as a fusion protein in Escherichia coli, and the product was detected by antibodies specific for the coat protein of BYMV. The predicted length of the coat protein gene was 822 nucleotides, corresponding to a 273 amino acid coat protein of Mr 30910. The deduced amino acid sequence of the BYMV coat protein was compared to the chemically determined amino acid composition of purified virion protein, and of protein prepared from trypsin-treated virions. The nucleotide and deduced amino acid sequences were compared to the sequences of the coat protein genes of other potyviruses. The BYMV coat protein gene was found to be 50 to 61% homologous to those of other potyviruses at both the nucleotide and amino acid levels; the greatest variation was between the 5'-proximal one-fifth of the genes. Amino acid sequences and hydrophilicity plots of the different potyvirus coat proteins showed similarities which indicated that the structure of the coat protein is highly conserved; a non-terminal region of variability was predicted to be exposed on the exterior of the virion. A putative cleavage site at a glutamine-serine dipeptide was identified by similarity in context to the cleavage sites of tobacco etch virus and tobacco vein mottling virus coat proteins from the viral polyproteins. The BYMV 3'-terminal non-coding region of 166 nucleotides is followed by a poly(A) tract.

Amino Acid Sequence

Nucleotide sequence of tomato ringspot virus RNA-2.

The sequence of tomato ringspot virus (TomRSV) RNA-2 has been determined. It is 7273 nucleotides in length excluding the 3' poly(A) tail and contains a single long open reading frame (ORF) of 5646 nucleotides in the positive sense beginning at position 78 and terminating at position 5723. A second in-frame AUG at position 441 is in a more favourable context for initiation of translation and may act as a site for initiation of translation. The TomRSV RNA-2 3' noncoding region is 1550 nucleotides in length. The coat protein is located in the C-terminal region of the large polypeptide and shows significant but limited amino acid sequence similarity to the putative coat proteins of the nepoviruses tomato black ring (TBRV), Hungarian grapevine chrome mosaic (GCMV) and grapevine fanleaf (GFLV). Comparisons of the coding and non-coding regions of TomRSV RNA-2 and the RNA components of TBRV, GCMV, GFLV and the comovirus cowpea mosaic virus revealed significant similarity for over 300 amino acids between the coding region immediately to the N-terminal side of the putative coat proteins of TomRSV and GFLV; very little similarity could be detected among the non-coding regions of TomRSV and any of these viruses.

Amino Acid Sequence

Nuclear DNA of plastid origin (NUPTs), neglected driver of genome variation and evolutionary innovation.

Plant nuclear genomes contain a variable, though typically minor, fraction of DNA sequences of plastid origin known as NUPTs. Unlike the massive transfer of DNA and genes from the proto-organelle genome to the nucleus that occurred during the endosymbiotic event that gave rise to plastids, the formation of NUPTs is an ongoing process that does not imply concomitant DNA loss. Although NUPTs are generally considered to be potentially deleterious insertions that are continuously generated and rapidly eliminated at near-constant turnover rates, accumulating evidence reveals alternative evolutionary trajectories. In this review, we discuss recent findings that highlight the episodic formation of NUPTs, their subsequent proliferation, and their eventual long-term fixation within the nuclear genome. We also explore their non-random spatial association with specific genomic elements. NUPTs show preferential overlap with specific superfamilies of transposable elements, which may facilitate their proliferation and dispersal throughout the nuclear genome. Regarding protein-coding genes, the contribution of NUPTs varies among species. In contrast, NUPTs are found to be consistently enriched among certain classes of non-coding RNA genes, notably rRNA, tRNA, and specific regulatory RNA families, suggesting that they are involved in the evolution of gene regulation and translational machinery. Overall, these findings underscore the unexpected complexity of the mechanisms underlying NUPT formation and support the idea that they are a significant source of genome variation and evolutionary innovation. Further research is necessary to fully elucidate the mechanisms underlying NUPT formation, as well as to determine their potential adaptive significance in plant genome evolution.

Plastids

Cloned proteolipid protein and myelin basic protein cDNA. Transcription of the two genes during myelination.

cDNA clones of rat brain proteolipid protein (PLP), also named lipophilin, the major integral myelin membrane protein, and of myelin basic protein (MBP), the major extrinsic myelin protein, have been isolated from a rat brain cDNA library cloned into the PstI site of pBR322. Poly(A)+ RNA from actively myelinating 18-day-old rats has been reversely transcribed. Oligonucleotides synthesized according to the established amino-acid sequence of lipophilin and the nucleotide sequence of the small myelin basic protein of the N-terminal, the central and C-terminal region of their sequences were used as hybridization probes for screening. The largest insert in one of several lipophilin clones was 2,585 base pairs (bp) in length (pLp 1). It contained 521 bp of the C-terminal coding sequence and the complete 2,064 bp long non-coding 3' sequence. The myelin basic protein cDNA insert of clones pMBP5 and pMBP6 is 2,530 bp long and that of clones pMBP2 and pMBP3 640 bp. These clones were also characterized. pMBP2 was sequenced and used together with the lipophilin cDNA clones as hybridization probes to estimate the lipophilin and myelin basic protein mRNA levels of rat brain during the myelination period. The expression of the lipophilin and myelin basic protein genes during development of the myelin sheath appears to be strictly coordinated.

Animals