SEARCH · PubMed Health

Results for “Molecular characterization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1992

Purification, cloning, and molecular characterization of a high molecular weight hemorrhagic metalloprotease, jararhagin, from Bothrops jararaca venom. Insights into the disintegrin gene family.

A large hemorrhagin, jararhagin, has been cloned from a Bothrops jararaca venom gland cDNA expression library. The cDNA sequence predicts a 421-amino acid residue molecule with strong amino acid sequence homology and similar domain structure to HR1B, a high molecular weight hemorrhagic metalloprotease isolated from Trimeresurus flavoviridis (Habu) venom. Like HR1B, jararhagin contains enzyme, disintegrin, and cysteine-rich carboxyl-terminal regions. In the disintegrin region, the Arg-Gly-Asp sequence is replaced by Glu-Cys-Asp, as found in non-Arg-Gly-Asp disintegrin regions of HR1B and a guinea pig sperm fusion protein PH-30 beta. The cDNA sequence of jararhagin predicts a precursor protein (proprotein) with striking similarity to cryptic regions in precursors of the disintegrin peptides trigramin and rhodostomin. Comparison of jararhagin with disintegrin precursors highlights the modular arrangement of proprotein, metalloprotease, and disintegrin domains in the metalloprotease/disintegrin family and provides an insight into their biosynthesis and evolution.

Amino Acid Sequence↗

PubMed2026

Molecular characterization of salivary cancers: Patterns of genomic alterations and potential for impact on therapeutic choices.

BACKGROUND: Salivary cancers are rare malignancies with diverse histologies, molecular landscape, and limited effective systemic therapy options. Recent tumour genomics research has identified driver alterations in salivary gland cancers that have led to personalized therapy approaches. The primary objective was to perform molecular characterization using next generation sequencing (NGS) panel and evaluate the potential impact of results on clinical decision-making and treatment outcomes. METHODS: Patients with locally advanced or incurable metastatic salivary cancers suitable for systemic therapy underwent NGS tumour testing with an amplicon-based DNA/RNA NGS panel. Patient demographics, baseline characteristics, treatment and treatment outcomes were retrospectively collected. RESULTS: From 2021 to 2024, 58 advanced salivary cancer patients underwent molecular characterization of their tumour. Baseline characteristics at diagnosis: male 60%, median age 67, most common histologies; adenoid cystic 27%, salivary duct 19% and mucoepidermoid 12%. PIK3CA alterations were the most common molecular finding across all subtypes 22% (13/58) and were enriched in salivary duct carcinoma 73% (8/11). Other alterations identified were: ERBB2 (4), EGFR (2), HRAS (3), NTRK3 (2), BRAF p.V600E (1), and RET (1). Immunohistochemistry identified androgen receptor positivity across salivary cancer subtypes in 8/19 and HER2 positivity in 2/20 tested. Twenty-two patients received systemic therapy prior to NGS results for incurable/metastatic disease, first line treatments included 69% chemotherapy, 18% anti-androgen, 9% lenvatinib, 4% trial. CONCLUSION: Molecular characterization of salivary cancers identified targetable alterations in 37% of patients. The identification of potential therapeutic targets offers the opportunity for expanded treatment options to benefit salivary gland cancer patients.

Metastatic salivary gland cancer↗

PubMed1992

Molecular characterization of a low-molecular-mass matrix metalloproteinase secreted by glomerular mesangial cells as PUMP-1.

A polymerase chain reaction (PCR)-based homology cloning strategy was used to define the spectrum of stromelysin-like matrix metalloproteinases (MMPs) synthesized by cultured glomerular mesangial cells (MC). Using this technique, cDNAs encoding an unusual, truncated member of the MMP family, punctuated (putative) metalloproteinase (PUMP-1), were exclusively isolated. Incubation with the cytokines interleukin 1 and tumour necrosis factor increased the abundance of PUMP-1 mRNA in mesangial cells. The mesangial PUMP-1 mRNA is processed in a tissue-specific manner, yielding a transcript containing repeated 3'-untranslated region ATTTA motifs commonly found in cytokines with limited mRNA stability. Polyclonal antibodies prepared against the C-terminal region of the PUMP-1 protein documented release of this enzyme by cultures of cytokine-stimulated MC and permitted identification of PUMP-1-expressing mesangial cells within clinical biopsy specimens of acute glomerulonephritis. These findings represent new molecular and clinical evidence that non-malignant cells process and secrete this unusual member of the MMP family in a cytokine-mediated, tissue-specific manner. Mesangial synthesis of PUMP-1 may contribute to the progression of injury during glomerular inflammatory states.

Amino Acid Sequence↗

PubMed2025

Isolation and Molecular Characterization of Three Staphylococcus pseudintermedius Strains from Dogs and Humans in Egypt.

Staphylococcus pseudintermedius is an opportunistic pathogen that is largely associated with canine hosts but is becoming more widely recognized as a zoonotic pathogen. Understanding its genetic and phenotypic properties, such as virulence factors and antimicrobial resistance (AMR) profiles, is critical for infection control and vaccine development. In this study, we isolated and molecularly characterized three S. pseudintermedius isolates from dogs (hereafter referred to as S. pseudintermedius D8) and humans (hereafter referred to as S. pseudintermedius H10 and S. pseudintermedius H11) in Egypt. All three isolates showed 100% sequence identity with the nuc gene of the S. pseudintermedius SP_11304-3A reference genome. Multilocus sequence typing (MLST) revealed novel sequence types (STs) in the three isolates. The AMR determinants varied substantially among the isolates. While the mecA gene was absent, blaZ was detected in the canine isolate, indicating beta-lactamase-mediated penicillin resistance. Additionally, tetK and tetM genes were found conferring tetracycline resistance in different isolates. Resistance genes for aminoglycosides, chloramphenicol, fusidic acid, macrolides, streptothricin, and trimethoprim were also identified. All isolates were positive for key virulence genes, including immune evasion (AdsA), coagulase (coa), immunoglobulin-binding protein (sbi/spsK), exfoliative toxin (speta), enterotoxins (se-int and siet), fibrinogen binding protein gene (fnbB), and two-component pore-forming leukocidin genes (lukF and lukS). The S. pseudintermedius H11 isolate uniquely harbored the neuraminidase gene (nanB), while none of the isolates contained the gene coding for immunoglobulin G binding protein (spsQ). These findings highlight the differences in virulence and antimicrobial resistance genes among these S. pseudintermedius isolates, underlining the need for global surveillance and molecular characterization of this pathogen.

Dogs↗

PubMedDate not supplied

Synthesis and molecular characterization of a biotinylated analog of [Lys]bradykinin.

We report the synthesis and molecular characterization of a biotinylated analog of kallidin, [Lys]bradykinin. Bradykinin was prepared by solid phase peptide synthesis. Before cleavage from the resin, a biotin moiety was coupled to the epsilon amino group of a lysine in the zeroth position of the bradykinin peptide. An omega-amino caproic acid spacer was incorporated between the biotin group and the N-terminal lysine. The biotinylated peptide was deprotected, cleaved from the resin and purified by RP-HPLC. The identity of this analog was confirmed by amino acid analysis and FAB-mass spectrometry. Biotinyl [Lys]bradykinin (BLBK, mol, wt. = 1528) inhibited [3H]-bradykinin binding to guinea pig ileum homogenates dose dependently, with an IC50 of 28.9 +/- 6 nM. The IC50 for [Lys]bradykinin was approximately 10-fold lower, 3.2 +/- 0.6 nM. BLBK induced contractility in an isolated guinea pig smooth muscle preparation with an EC50 of 129 +/- 14 nM; the corresponding value for [Lys]bradykinin was 29 +/- 8 nM. These data are consistent with the difference in binding potency observed for BLBK compared to [Lys]bradykinin. In an ELISA assay using BLBK and affinity-purified rabbit anti-bradykinin antibody, BLBK bound to anti-bradykinin antibody with an EC50 = 1.21 +/- 0.54 nM. Rank order potencies for several bradykinin peptide analogs suggest that the epitope on bradykinin recognized by the antibody is likely to be at the carboxy terminus of the peptide.

Amino Acid Sequence↗

PubMed2026

Emergence of two novel HIV-1 Circulating Recombinant Forms (CRF190_0708 and CRF191_0708): molecular characterization and clinical insights from a five-year study in Yunnan, China.

BACKGROUND: To characterize HIV-1 molecular epidemiology and identify novel circulating recombinant forms (CRFs) among antiretroviral therapy (ART)-naïve heterosexuals in Yunnan, China, and evaluate their clinical impact. METHODS: This study examined 636 HIV-1 pol sequences to analyze genetic diversity, pretreatment drug resistance (PDR), and transmission networks. Near full-length genomes were obtained to identify and characterize novel recombinants, with their evolutionary history inferred by Bayesian analysis. Co-receptor tropism was predicted, and the five-year clinical outcomes (including immune reconstitution and virologic response) of patients infected with the novel CRFs were compared. RESULTS: The most prevalent type identified was CRF08_BC, accounting for 50.16% of cases. The prevalence of drug resistance was 5.97% (38/636), with the K103N mutation being the most common. An analysis of transmission networks revealed that 52.2% (272/521) of clusters were associated with CRF07_BC and CRF08_BC. Two novel second-generation CRFs were identified: CRF190_0708, with an estimated time to the most recent common ancestor (tMRCA) of 1998.9, and CRF191_0708, with a more recent tMRCA ranging from 2009.5 to 2011.6. During the five-year follow-up period, viral rebound was observed in 7 patients in the CRF190_0708 group and in 1 patient in the CRF191_0708 group. Drug-resistance mutations (M184V and K103N) were detected in a subset of rebound cases in the CRF190_0708 group. CONCLUSIONS: This study identifies two novel HIV-1 recombinants, CRF190_0708 and CRF191_0708, highlighting ongoing viral evolution in Yunnan. Preliminary findings suggest possible clinical differences, warranting further investigation. Continued molecular surveillance is needed. TRIAL REGISTRATION: The clinical study was registered at ClinicalTrials.gov under the identifier NCT03852849. The date of registration was March 22, 2019.

Adult↗

PubMed1992

Ependymins from the cerebrospinal fluid of salmonid fish: gene structure and molecular characterization.

So far, ependymins (Epds) have been sequenced only from cypriniform fish, and in the past all attempts have failed to characterize, on a molecular level, homologous Epd proteins in higher vertebrates. Therefore, rainbow trout (Oncorhynchus mykiss) Epds, which represent the predominant proteins of the cerebrospinal fluid, have been N-terminally sequenced and the encoding cDNA subsequently cloned using the polymerase chain reaction. Surprisingly, only 40-42% of the amino acids are identical with the corresponding sequences from goldfish (Carassius auratus), and no convincing immunological cross-reactivity is observed with an antiserum raised against purified Epds from C. auratus. O. mykiss possesses two highly homologous genes encoding Epds (Om-I, Om-II), a feature typical of a quasi-tetraploid species. Western analysis, using two specific antibodies against Epds from O. mykiss, revealed a variety of different glycosylation variants. In contrast to C. auratus, Epds from O. mykiss probably do not form disulfide-linked dimers. The structure of one Epd gene and its flanking regions have been determined for the Atlantic salmon (Salmo salar). Six exons were deduced by comparison with the corresponding cDNA sequence from O. mykiss (almost 98% homology with Om-II).

Amino Acid Sequence↗

PubMed2026

The prevalence and molecular characterization of Porcine teschoviruses in Guangdong Province, China.

Porcine teschoviruses (PTVs) are globally endemic and widely circulate within pig populations. This study aimed to investigate the prevalence and genetic characteristics of PTVs in Guangdong Province, China. A total of 341 fecal and 99 tissue mixture samples were collected from pigs in seven cities across the province. These samples were screened for PTVs using reverse transcription-polymerase chain reaction (RT-PCR). The overall PTV positivity rate was determined to be 19.32%. In this study, the PTV3 PTV/CN/GD/316 strain was successfully isolated from a tissue mixture sample obtained from a pig exhibiting diarrhea. The isolation was performed using swine testicular (ST) cells. The complete viral genome of this isolate measured 6,999 nucleotides (nt) and encoded a polyprotein of 2,205 amino acids. Phylogenetic analysis of the complete VP1 gene identified seven distinct PTV genotypes (PTV2, PTV3, PTV4, PTV9, PTV14, PTV17, and PTV19) among the 21 PTV isolates obtained, with PTV3 being the dominant genotype (38.10%), followed by PTV9 (19.05%). Furthermore, our findings revealed a significant co-infection of PTVs with other common swine pathogens, including PCV2, PEDV, PCV3, PRRSV, CSFV, and PDCoV. The co-infection rate with these viruses was remarkably high, reaching 97.65%. Collectively, these data demonstrate the widespread circulation of PTVs in pig farms in Guangdong Province and highlight the prevalence of co-infection scenarios with other viral agents. The genetic analyses of all available PTV VP1 sequences also underscore the considerable diversity of PTV genotypes circulating within the Guangdong region.IMPORTANCECurrently, PTVs are widespread globally, with their infection rates showing a rising trend. The prevalence and molecular characterization of PTVs help prevent and control the spread of diseases. The findings of this study indicate a high prevalence and considerable genetic diversity of PTVs in certain areas of Guangdong Province, China. The occurrence of co-infection with other pathogens is also relatively common. Based on these data, we can better safeguard swine health and mitigate the economic impact of these infections on the agricultural industry.

Guangdong Province↗

PubMed1992

Molecular characterization of two galactosemia mutations and one polymorphism: implications for structure-function analysis of human galactose-1-phosphate uridyltransferase.

We report here the molecular characterization of two galactosemia mutations, L74P and F171S, and one polymorphism, S135L, in human galactose-1-phosphate uridyltransferase (GALT). Both galactosemia mutations result in reduced enzymatic activity when reconstructed in the cDNA and overexpressed. The polymorphism, in contrast, has near normal activity. Both mutations affect evolutionarily conserved residues, suggesting that they are functionally important, while the polymorphism occurs in a nonconserved domain which is presumably not critical for enzymatic function. The F171S mutation is close to the putative active-site nucleophile. Our data further support the notion of molecular heterogeneity of galactosemia and suggest that galactosemia mutations and GALT polymorphisms may be useful tools in highlighting different functional domains in human GALT.

Base Sequence↗

PubMed1992

An ocular melanoma-associated antigen. Molecular characterization.

Monoclonal antibody (MAb) 8-1H defines a highly conserved ocular melanoma-associated antigen. Based on a potential binding site of MAb8-1, we identified, molecularly cloned, and sequenced the gene, encoding this melanoma-associated antigen from a uveal melanoma copy DNA library. Nucleotide sequence analysis of the melanoma-associated antigen revealed characteristics of a membrane-bound protein of 238 amino acids (approximately 25 kd) with four transmembrane domains. The sequence of the ocular melanoma-associated antigen is identical to the sequence of a recently reported cutaneous melanoma-associated antigen, substantiating our previous studies regarding common antigens between ocular and cutaneous melanoma. In addition, the melanoma-associated antigen shares sequence homology with a number of transmembrane proteins that appear to be involved in growth regulation. The implication of the biological function of this ocular melanoma-associated antigen, its relevance to the malignant phenotype, and clinical applications of the molecular characterization of this melanoma-associated antigen are described.

Amino Acid Sequence↗

PubMed1992

Molecular characterization of areas with low grade tumor or satellitosis in human malignant astrocytomas.

Malignant astrocytomas often display histopathological heterogeneity. In the present study, we have molecularly characterized different areas within 4 such tumors to determine whether the tissue heterogeneity can be explained by differences in DNA constitution. Two tumors contained low grade areas, and the other 2 had areas with satellitosis. The tumors were examined for loss of heterozygosity with markers from chromosomes 9p, 10, and 17p and for amplification of the epidermal growth factor receptor gene. In each case, the high grade portion of the tumor displayed at least one of these structural alterations. However, identical alterations were found in the associated low grade or satellitosis areas of each tumor. Our data suggest that: (a) genetic alterations associated with tumor progression already occur in histopathologically low grade areas of high grade astrocytoma; (b) satellitosis associated with a high grade astrocytoma has to be considered as part of that tumor; and (c) tissue heterogeneity within a high grade astrocytoma is not a consequence of differences in DNA constitution at the loci that were examined.

Astrocytoma↗

PubMed2025

Cytogenetic and molecular characterization of an atypical ETP-ALL case with BCL2 dependency: therapeutic implications for Venetoclax use.

BACKGROUND: Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a rare, high-risk subtype of T-ALL characterized by distinctive immunophenotypic and genomic features. It is often associated with induction failure and frequent relapses. Despite recent advances in its molecular characterization, the prognosis remains dismal, and effective targeted therapies are limited. METHODS AND RESULTS: We report a pediatric, multi-refractory ETP-ALL case with novel cytogenetic alterations, including a 4q deletion and a t(16;18)(q24;q21) translocation. Molecular profiling revealed progressive activation of the BCL2 pathway and disruption of Th17-related immune markers. Ex vivo sensitivity assays performed at different disease stages demonstrated increasing BCL2 dependency. Based on these findings, venetoclax was administered on a compassionate-use basis, resulting in rapid hematologic recovery and a marked reduction in blast percentage. CONCLUSIONS: This case highlights the role of clonal evolution and immune deregulation in accompanying BCL2 addiction in relapsed ETP-ALL. Altogether, our findings underscore the therapeutic potential of venetoclax in refractory pediatric ETP-ALL cases with progressive BCL2 dependency.

Humans↗

PubMed1992

Molecular characterization of a Drosophila melanogaster variant strain defective in the Sgs-4 gene dosage compensation.

The X-linked Sgs-4 gene of Drosophila melanogaster encodes a salivary glue protein. Here we report the molecular characterization of a non-dosage compensated variant strain, named Karsnas, in which males accumulate only about half of the Sgs-4 polypeptide amount as do females. The results obtained show that significant nucleotide sequence alterations are accumulated within the Sgs-4 coding and 3' untranslated region of the variant strain, thus suggesting a possible role of these sequences in the Sgs-4 dosage compensation.

Animals↗

PubMedDate not supplied

[Metabolically stable classes of nuclear messenger-like RNA. I. Detection and molecular characterization].

Two discreet in size molecular classes of metabolically stable messenger-like RNA molecules with sedimentation coefficientes about 28S and 18S have been revealed in the nuclei of pigeon bone marrow cells. The structural pecularities of 28S RNA class were investigated more carefully. It was shown to constitute the largest fraction of nuclear messenger-like RNA and is characterized by a GC/AU ratio 1.13. As pulse-labeled nuclear RNA, 28S stable nuclear RNA hybridizes with the unique and rare repeated DNA, it does not contain poly(A)-sequences and is found in a form of RNP particles with density of 1.41 g/sm3, tightly bound to chromatin.

Animals↗

PubMed1992

Molecular characterization of congenital mesoblastic nephroma and its distinction from Wilms tumor.

BACKGROUND: Congenital mesoblastic nephroma (CMN) is a rare tumor of the neonatal kidney. It was once thought to be a variant of Wilms tumor that also arises from primitive renal cells. METHODS: Molecular characteristics of two CMN were studied to clarify their potential relationship to Wilms tumors. Patterns of gene expression were assayed by Northern blot hybridization analysis. Tumors were tested for loss of heterozygosity (LOH) at chromosomes 11p13 and 11p15 using Southern blot analysis. RESULTS: The CMN, like Wilms tumors, demonstrated high-level expression of insulin-like growth factor II. Unlike Wilms tumors, however, the CMN expressed neither the N-myc oncogene nor the putative Wilms tumor suppressor gene, WT1. Using a panel of probes spanning 11p13 and 11p15, no LOH was detected in the CMN, nor was there evidence of deletion or rearrangements of WT1. CONCLUSIONS: Although Wilms tumor and CMN both arise from the developing kidney, molecular characterization suggests that different factors are involved in the pathogenesis of these two tumors.

Chromosome Mapping↗

PubMed1992

Molecular characterization of chromosome 22 deletions in schwannomas.

Schwannomas are tumors of the cranial, spinal, and peripheral nerve sheaths that originate from Schwann cells. Acoustic neurinomas are the most frequent cranial schwannomas. They might develop sporadically or in the context of neurofibromatosis type 2 (NF2). Loss of part or all of chromosome 22 is frequently found in acoustic schwannomas, suggesting that the NF2 gene is a tumor suppressor gene involved in the genesis of these tumors. Only a few spinal schwannomas have been molecularly characterized so far, showing that chromosome 22 loss might also occur in these tumors. Here we present the molecular analysis of chromosome 22 in 23 acoustic schwannomas and nine schwannomas of other locations (including other cranial nerves and spinal and peripheral nerves). Most of these tumors were from sporadic cases. Multiple schwannomas of various locations were analyzed in two patients with NF2. We found partial or complete monosomy for chromosome 22 in 22% of the acoustic schwannomas and 55% of the non-acoustic schwannomas. The tumors with partial monosomy included four with terminal deletions and one with a deletion of the centromeric part of the long arm of chromosome 22. The region between the beta B2-1 crystallin locus (CRYB2A) and the myoglobin locus (MB) was commonly deleted in these tumors. Our studies suggest that a schwannoma-related tumor suppressor gene within this region, which might be the NF2 gene, is involved in the development of schwannomas of various locations in the nervous system. Our studies indicate that the second hit in the genesis of different schwannomas within one (predisposed) NF2 patient occurs independently and via different mechanisms.

Blotting, Southern↗

PubMed2025

Molecular characterization of colistin resistance in carbapenem-resistant Klebsiella pneumoniae from a tertiary hospital in China.

Colistin resistance in carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a significant global health challenge, as colistin remains the last-resort antibiotic for treating multidrug-resistant K. pneumoniae infections. This study aimed to investigate the prevalence and molecular mechanisms underlying colistin resistance in CRKP (Colr-CRKP) isolates in Henan, China, from 2021 to 2024. The minimum inhibitory concentrations of colistin for 134 K. pneumoniae isolates were determined using the broth microdilution method. Whole-genome sequencing was performed using the Illumina platform to identify carbapenemase genes and sequence types (STs). Colistin resistance mechanisms were investigated, including mutations in two-component systems (pmrA/pmrB, phoP/phoQ), inactivation of the mgrB gene, and the presence of plasmid-mediated mcr genes. Most isolates were collected from intensive care units (99/134, 73.9%), with 48.5% (59/134) of patients having no documented colistin exposure history. Notably, ST11 was the predominant sequence type among Colr-CRKP isolates (113/134, 84.3%), all of which carried blaKPC-2 as the sole carbapenemase determinant. In contrast, seven non-carbapenemase-producing isolates exhibited phenotypic resistance to carbapenems. Genomic analysis revealed inactivation or loss of the mgrB gene in 53.7% (72/134) of isolates, predominantly due to insertion mutations (54/72). Although 32.8% (44/134) of isolates carried mutations in two-component systems, these alterations did not exhibit pathway-specific clustering. Intriguingly, plasmid-mediated mcr genes were detected in only 1.5% (2/134) of cases (mcr-8.2 and mcr-1.1), while 22.4% (30/134) of colistin-resistant strains lacked identifiable resistance determinants based on current detection methods. Our findings indicate that disruption of the mgrB gene is the primary mechanism of colistin resistance in ST11 CRKP clones. The emergence of resistance in 48.5% of patients without prior colistin exposure, combined with low mcr gene prevalence (1.5%) and unexplained resistance in 22.4% of isolates, suggests complex selective pressures beyond direct antimicrobial use. These findings underscore the urgent need for strengthened antimicrobial stewardship and the development of alternative therapeutic strategies to combat this high-risk pathogen.IMPORTANCEThe global rise of colistin-resistant Klebsiella pneumoniae, particularly in carbapenem-resistant Klebsiella pneumoniae (CRKP) strains, has severely restricted treatment options for multidrug-resistant infections. Our study provides the first comprehensive molecular characterization of colistin resistance in CRKP in a large tertiary hospital in central China. We identified mgrB disruption as the predominant resistance mechanism, while plasmid-mediated mcr genes were rare. Notably, nearly half of the resistant isolates occurred in patients without prior colistin exposure, suggesting alternative selective pressures driving resistance. These findings highlight the complex dynamics of colistin resistance in CRKP and underscore the need for enhanced genomic surveillance and stewardship interventions to limit further dissemination.

Colistin↗

PubMed1991

Molecular characterization of the trithorax gene, a positive regulator of homeotic gene expression in Drosophila.

The Drosophila gene trithorax (trx) is required for the normal expression of a number of the homeotic genes in the bithorax complex (BX-C) and the Antennapedia complex (ANT-C). Flies homozygous for trx mutations exhibit segmental identity transformations similar to those caused by loss-of-function mutations in the homeotic genes Sex combs reduced (Scr), Ultrabithorax (Ubx), abdominal-A (abd-A), and Abdominal-B (Abd-B). We present a molecular characterization of the trx locus and show that it is necessary for normal levels of Antennapedia (Antp), Ubx, and abd-A protein accumulation. Interestingly, the loss of trx function differentially affects the expression these proteins; Ubx protein levels are greatly reduced, abd-A protein levels are reduced to a lesser extent, and Antp protein levels are only slightly reduced. P-element mediated transformation using 34 kb of genomic DNA containing the 25 kb trx transcription unit identifies all sequences necessary for normal trx function and limits the 5' and 3' flanking sequences that could be used in a regulatory capacity to relatively small regions. The primary transcription unit is differentially spliced to produce two large transcripts of 12 and 15 kb that have different developmental profiles.

Animals↗