SEARCH · PubMed Health

Results for “Multigene Family”

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 55 records · Page 3Linked to original sources

PubMed1998

Evolution of multigene families by gene duplication. A haploid model.

Evolution of multigene families by gene duplication and subsequent diversification is analyzed assuming a haploid model without interchromosomal crossing over. Chromosomes with more different genes are assumed to have higher fitness. Advantageous and deleterious mutations and duplication/deletion also affect the evolution, as in previous studies. In addition, negative selection on the total number of genes (copy number selection) is incorporated in the model. First, a Markov chain approximation is used to obtain formulas for the average numbers of different alleles, genes without pseudogene mutations, and pseudogenes assuming that mutation rates and duplication/deletion rates are all very small. Computer simulation shows that the approximation works well if the products of population size with mutation and duplication/deletion rates are all small compared to 1. However, as they become large, the approximation underestimates gene numbers, especially the number of pseudogenes. Based on the approximation, the following was found: (1) Gene redundancy measured by the average number of redundant genes decreases as advantageous selection becomes stronger. (2) The number of different genes can be approximately described by a linear pure-birth process and thus has a coefficient of variation around 1. (3) The birth rate is an increasing function of population size without copy number selection, but not necessarily so otherwise. (4) Copy number selection drastically decreases the number of pseudogenes. Available data of mutation rates and duplication/deletion rates suggest much faster increases of gene numbers than those observed in the evolution of currently existing multigene families. Various explanations for this discrepancy are discussed based on our approximate analysis.

Alleles↗

PubMed1990

Genetic variation and multigene families in African swine fever virus.

The genome of a virulent strain (LIS57) of African swine fever virus differs from that of the Vero-cell-adapted strain (BA71V) in several deletions located in the variable regions. The region which contains the most differences is located 8-20 kb from the left end. The DNA sequence of this region was obtained from LIS57 virus DNA and compared with the overlapping sequences of BA71V virus. This comparison revealed that the changes in the variable regions result in differences in the number of genes which belong to the multigene families 360 and 110. Virus isolate LIS57 contains at least 8 genes of the multigene family 360 and 12 genes of the multigene family 110, instead of the 6 and 5 genes, respectively, found in BA71V virus strain. The position of the deletions indicates that new combinations of multigene family members in African swine fever virus DNA may arise by in-frame recombination between homologous genes. These data indicate that the evolution of the multigene families 360 and 110 in African swine fever virus DNA has involved different processes, including gene duplication, divergence of duplicated genes, and gene deletion.

African Swine Fever Virus↗

PubMed2002

Characterization of the gene conversions between the multigene family members of the yeast genome.

Stanley Sawyer's gene conversion detection method, implemented in his GENECONV computer program, was used to detect and characterize the gene conversions between the multigene family members of the yeast genome. This method gave different gene conversion frequencies and size distribution for gene families with two members and multigene families with more than two members. The 69 gene conversions detected in multigene families with more than two members occur at a frequency of 7.8% gene conversion/pair of genes compared and have an average size of 173+/-220 nucleotides. Larger gene conversions are found only between more similar genes, the genes involved in gene conversions are distributed almost randomly among the 16 yeast chromosomes, and the frequency of gene conversions increases as the distance between repeated genes decreases. In contrast to previous studies, no relationship was observed between the level of expression of a gene and its involvement in gene conversions. These analyses also suggest that gene conversions might occur by different mechanisms in closely linked genes and unlinked genes. The excess of converted regions at the 3? end of unlinked genes suggests that recombination with incomplete cDNA molecules is the main mechanism responsible for gene conversions between such genes.

Evolution, Molecular↗

PubMed1996

Size and genomic location of the pMGA multigene family of Mycoplasma gallisepticum.

The pMGA multigene family encodes variant copies of the cell surface haemagglutinin of Mycoplasma gallisepticum. Quantitative Southern blotting, using an oligonucleotide probe complementary to a region conserved in the leader sequence of all known pMGA genes, was used to estimate the number of members of the family in the genome of seven strains of M. gallisepticum. The number of copies estimated to be present in the genome varied from 32 in strain F to 70 in strain R, indicating that the pMGA gene family may be second in size only to the tRNA family among prokaryotes. If all members of the pMGA family are of similar length to those which have been characterized, a minimum of 79 kb (7.7%) of the genome of strain S6, 82 kb (8.2%) of PG31 and 168 kb (16%) of the genome of strain R is dedicated to encoding variants of the same haemagglutinin. The GAA repeat motif identified in the intergenic region between all characterized pMGA genes appeared to be a feature common to most, if not all, pMGA genes, and furthermore probably exclusive to them. The genomic locations of members of the pMGA family were determined by PFGE and Southern blot hybridization of M. gallisepticum strain S6. The hybridizing regions were localized to four separate regions on the chromosome. The pMGA genes are likely to be predominantly arranged as tandem repeats within these regions, similar to the restricted regions for which the genomic sequence has been determined.

Antigenic Variation↗

PubMed1985

Assignment of human gamma crystallin multigene family to chromosome 2.

The multigene family for human gamma-crystallin has been assigned to chromosome 2 using rodent-human somatic cell hybrids and filter hybridization analysis of cell hybrid DNA. Two genomic DNA probes containing human gamma-crystallin gene sequences hybridize to five fragments in human DNA digested with the restriction enzyme EcoRI. By correlating the presence of these fragments in somatic cell hybrid DNA with the human chromosome content of the hybrids, at least six human gamma-crystallin genes can be mapped to chromosome 2. Data obtained with a hybrid clone containing a mouse-human interspecies translocation suggest that these genes may be clustered together on the long arm of human chromosome 2.

Animals↗

PubMed1989

Chromosomal protein HMG-14. Identification, characterization, and chromosome localization of a functional gene from the large human multigene family.

The human HMG-14 multigene family is one of the largest retropseudogene families known. To identify and isolate a functional human HMG-14 gene, genomic clones, selected with the cDNA, were screened with a set of 6 oligonucleotides. A single genomic clone was isolated suggesting that the human genome contains few, and perhaps only one, functional genes. An 8882-base pair (bp) genomic clone containing the complete, 6804-bp-long human gene together with 850 bp 5' to the start of transcription and 1228 bp 3' to the end of transcription was sequenced. The gene is comprised of 6 exons ranging in size from 30 to 839 bp, two of which code for the entire DNA binding site of the protein, and has several features typical of "housekeeping" genes. Using human-rodent somatic cell hybrids, the HMG-14 gene was localized to human chromosome 21. A restriction fragment length polymorphism, useful for further analysis and mapping, has been detected. The present article, which describes the first isolation and characterization of a gene coding for chromosomal protein HMG-14, indicates that genes coding for HMG-14 and HMG-17 may share several distinctive characteristics. Comparison with the human and chicken HMG-17 genes reveals that all contain 6 exons, that all have exons of similar size, that all have 5' regions highly enriched in GC residues and that all have features typical of housekeeping genes.

Animals↗

PubMed2005

Developing antibodies to synthetic peptides based on comparative DNA sequencing of multigene families.

Using antisera to analyze the expression of specific gene products is a common procedure. However, in multigene families, such as the beta-keratins of the avian integument where strong homology exists among the scale (ScbetaK), claw (ClbetaK), feather (FbetaK), and feather-like (FlbetaK) subfamilies, determining the cellular and tissue expression patterns of the subfamilies is difficult because polyclonal antisera produced from any one protein recognize all family members. Traditionally, researchers produced and screened multiple monoclonal antisera produced from the proteins of interest until an antiserum with sufficient specificity could be obtained. Unfortunately, this approach requires a lot of effort, and once obtained, such antisera may have limited applications. Here, we present procedures by which comparative DNA sequences of members from the beta-keratin multigene family were translated and aligned to identify amino acid domains that were conserved within the FbetaK subfamily, but which were divergent from the other subfamilies. A synthetic 23-mer peptide with the conserved amino acid sequence was generated and used to produce a polyclonal antiserum that recognizes only the FbetaK subfamily of proteins. Western blot analysis and confocal microscopy with this antiserum are now providing valuable new insights concerning the developmental and evolutionary relationships between the scale, claw, and feather proteins found in birds. This represents a powerful new approach combining techniques from molecular evolution and developmental biology to study the expression and evolution of specific members of multigene families.

Amino Acid Sequence↗

PubMed2001

Sequence comparisons among dispersed members of the Brassica S multigene family in an S9 genome.

Self-incompatibility (SI) systems prevent self-pollination and promote outbreeding. In Brassica, the SI genes SLG (for S-locus glycoprotein) and SRK (for S-receptor kinase) are members of the S multigene family, which share the SLG-like domain (S domain), which encodes a putative receptor. We have cloned members of the S multigene family from the S9 haplotype of B. campestris (syn. rapa). In addition, eight distinct genomic regions harboring 10 SLG/SRK-like genes were characterized in the present study. Sequence analysis revealed two novel SRK-like genes, BcRK3 and BcRK6 (for B. campestris receptor kinases 3 and 6, respectively). Other genes that were characterized included SFR2 (for S gene family receptor 2), SLR2 (for S locus related gene 2), and a pseudogene. Based on phylogenetic analysis of the nucleotide sequences of the S domain regions, SLG and SRK appear to be distinct from other members of the S multigene family. Linkage analysis showed that most members of the S multigene family are dispersed in the Brassica genome, and that SLR1 (S locus related gene 1) is not linked to the SLR2 in B. campestris.

Blotting, Southern↗

PubMed1985

Inheritance, organization, and mapping of rbcS and cab multigene families in pea.

DNA restriction endonuclease fragment patterns corresponding to both the rbcS and cab multigene families of pea are each shown to segregate as single Mendelian units in the F(2) progeny of two separate crosses. All of the observed variation in each of the multigene families is thus organized on the chromosome in a tightly linked complex. Linkage relationships between both multigene families and an array of morphological and isozyme markers establish the location of the rbcS and cab gene clusters on pea chromosomes 5 and 2, respectively. Our results, which indicate a high level of DNA restriction fragment length polymorphism in pea, suggest sufficient variation to permit the construction of a highly detailed linkage map.

Journal Article↗

PubMed1997

Evolution by the birth-and-death process in multigene families of the vertebrate immune system.

Concerted evolution is often invoked to explain the diversity and evolution of the multigene families of major histocompatibility complex (MHC) genes and immunoglobulin (Ig) genes. However, this hypothesis has been controversial because the member genes of these families from the same species are not necessarily more closely related to one another than to the genes from different species. To resolve this controversy, we conducted phylogenetic analyses of several multigene families of the MHC and Ig systems. The results show that the evolutionary pattern of these families is quite different from that of concerted evolution but is in agreement with the birth-and-death model of evolution in which new genes are created by repeated gene duplication and some duplicate genes are maintained in the genome for a long time but others are deleted or become nonfunctional by deleterious mutations. We found little evidence that interlocus gene conversion plays an important role in the evolution of MHC and Ig multigene families.

Animals↗

PubMed1991

A comprehensive analysis of the developmental and tissue-specific expression of the isoactin multigene family in the rat.

The present study represents the first comprehensive analysis of isoactin gene expression in the developing rat. Our results clearly demonstrate that the developmental and tissue-specific expression of the actin multigene family is a highly integrated and complex process involving a variety of regulatory paradigms. The distinct temporal patterns of expression reported in this study indicate that there are three key phases in the regulation of expression of the actin multigene family during development. These include early embryonic development, late fetal development, and early postnatal development. The specific spatial patterns of expression observed in this study demonstrate that the expression of the actin multigene family is much more permissive than previously reported. This permissive expression includes a wide range of "ectopic" expression of the striated muscle isoactins as well as an extended expression of the alpha-smooth muscle isoactin. These findings expand our current understanding of the expression of the actin multigene family in development and provide a fundamental basis for future studies directed at investigating these processes.

Actins↗

PubMed1997

Three members of the S multigene family are linked to the S locus of Brassica.

Two self-incompatibility genes in Brassica, SLG and SRK (SLG encodes a glycoprotein; SRK encodes a receptor-like kinase), are included in the S multigene family. Products of members of the S multigene family have an SLG-like domain (S domain) in common, which may function as a receptor. In this study, three clustered members of the S multigene family, BcRK1, BcRL1 and BcSL1, were characterized. BcRK1 is a putative functional receptor kinase gene expressed in leaves, flower buds and stigmas, while BcRL1 and BcSL1 are considered to be pseudogenes because deletions causing frameshifts were identified in these sequences. Sequence and expression pattern of BcRK1 were most similar to those of the Arabidopsis receptor-like kinase gene ARK1, indicating that BcRK1 might have a function similar to that of ARK1, in processes such as cell expansion or plant growth. Interestingly, the region containing BcRK1, BcRL1 and BcSL1 is genetically linked to the S locus and the physical distance between SLG, SRK and the three S-related genes was estimated to be less than 610 kb. Thus the genes associated with self-incompatibility exist within a cluster of S-like genes in the genome of Brassica.

Amino Acid Sequence↗

PubMed1998

Multiple recombination events maintain sequence identity among members of the nitrogenase multigene family in Rhizobium etli.

A distinctive characteristic of the Rhizobium genome is the frequent finding of reiterated sequences, which often constitute multigene families. Interestingly, these families usually maintain a high degree of nucleotide sequence identity. It is commonly assumed that apparent gene conversion between reiterated elements might lead to concerted variation among members of a multigene family. However, the operation of this mechanism has not yet been demonstrated in the Rhizobiaceae. In this work, we employed different genetic constructions to address the role of apparent gene conversion as a homogenizing mechanism between members of the plasmid-located nitrogenase multigene family in Rhizobium etli. Our results show that a 28-bp insertion into one of the nitrogenase reiterations can be corrected by multiple recombination events, including apparent gene conversion. The correction process was dependent on the presence of both a wild-type recA gene and wild-type copies of the nitrogenase reiterations. Frequencies of apparent gene conversion to the wild-type nitrogenase reiterations were the same when the insertion to be corrected was located either in cis or in trans, indicating that this event frequently occurs through intermolecular interactions. Interestingly, a high frequency of multiple crossovers was observed, suggesting that these large plasmid molecules are engaging repeatedly in recombination events, in a situation akin to phage recombination or recombination among small, high-copy number plasmids.

Base Sequence↗

PubMed1995

Evidence for gene conversion in the amylase multigene family of Drosophila pseudoobscura.

The alpha-amylase (Amy) multigene family in Drosophila pseudoobscura is located on the third chromosome, which is polymorphic for more than 40 inverted gene arrangements. The number of copies in this family ranges from one to three, depending on the arrangement in question. A previous study of the three Amy genes from the Standard (ST) arrangement suggested either that duplicated copies (Amy2 and Amy3) are functionally constrained or that they are undergoing gene conversion with Amy1. In order to elucidate further the pattern of molecular evolution in this family, we cloned and sequenced four additional Amy genes, two from the Santa Cruz (SC) and two from the Chiricahua (CH) gene arrangement. Of the two alternatives, only the hypothesis of gene conversion is supported by the sequence analysis. The homogenization effect of gene conversion has been strongest in SC, whose copies differ by only two nucleotides, less noticeable in ST, and negligible in the CH. Furthermore, the action of gene conversion is apparently localized, occurring only in the coding region. Interestingly, these results concur with the findings of other workers for the duplicated Amy genes in the Drosophila melanogaster group. Thus, the occurrence of gene conversion in the Amy multigene family seems to be a common feature in the Drosophila species studied so far.

Animals↗

PubMed2000

Organization and structural evolution of four multigene families in Arabidopsis thaliana: AtLCAD, AtLGT, AtMYST and AtHD-GL2.

The Arabidopsis Genome Initiative has released up to now more than 80% of the genome sequence of Arabidopsis thaliana. About 70% of the identified genes have at least one paralogue. In order to understand the biological function of individual genes, it is essential to study the structure, expression and organization of the entire multigene family. A systematic analysis of multigene families, made possible by the amount of genomic sequence data available, provides important clues for the understanding of genome evolution and plasticity. In this paper, four multigene families of A. thaliana are characterized, namely LCAD, HD-GL2, LGT and MYST. Members of HD-GL2 and LCAD have already been reported in plants. The LGT genes specify proteins containing motifs of glycosyl transferase. No plant genes similar to the LGT genes have been reported to date. The novel MYST family, most likely plant-specific, encodes proteins with no identified function. Sequencing and in silico analysis led to the characterization of 29 novel genes belonging to these four gene families. The organization, structure and evolution of all the members of the four families are discussed, as well as their chromosome location. Expression data of some of the paralogues of each family are also presented.

Alcohol Oxidoreductases↗

PubMed1982

Saccharomyces cerevisiae contains a complex multigene family related to the major heat shock-inducible gene of Drosophila.

Saccharomyces cerevisiae contains a family of genes related to the major heat shock-induced gene of Drosophila (hsp 70). Two members of the multigene family (YG100 and YG101) were isolated. The primary DNA sequences of more than one-half of the protein-encoding regions of YG100 and YG101 were determined and compared with the Drosophila hsp 70 gene sequence; the predicted amino acid sequences were 72 and 64% homologous to the sequence of the Drosophila hsp 70 protein, respectively. The predicted amino acid sequences of the yeast genes were 65% homologous. Our results demonstrate a striking sequence conservation of hsp 70-related sequences in evolution. Hybridization of the S. cerevisiae genes to total S. cerevisiae DNA indicated that the multigene family consists of approximately 10 members. Hybridization of labeled RNAs from heat-shocked and control cells suggested that, like transcription of the Drosophila hsp 70 gene, transcription of YG100 or a closely related gene is enhanced after heat shock. However, the amount of RNA sequences homologous to YG101 was reduced after heat shock. A multigene family related to the hsp 70 gene exists in Drosophila; transcription of some members is induced by heat shock, whereas transcription of others is not. Our results suggest that S. cerevisiae, like Drosophila, contains a multigene family of hsp 70-related sequences under complex transcriptional regulation and that the differential control, as well as the nucleotide sequence, has been highly conserved in evolution.

Amino Acid Sequence↗

PubMed1996

A novel multigene family that the gene for a maize DNA-binding protein, MNB1a belongs to: isolation of genomic clones from this family and some aspects of its molecular evolution.

MNB1a is a DNA-binding protein of maize that contains a unique DNA-binding domain, designated the Dof domain, and its gene belongs to a multigene family. In putative proteins encoded by cDNA clones of the multigene family, the Dof domain was strongly conserved. In this study, two maize genomic clones of this multigene family were isolated. Although these clones did not contain the MNB1a gene, RNA transcripts corresponding to genomic clones were detected, suggesting that the clones encode authentic proteins. These clones contained sequences homologous to a portion of the sequence of the MNB1a cDNA. Unexpectedly, however, this region did not correspond to the Dof domain but to a region just downstream of the Dof domain. Although these observations seemed to suggest that the MNB1a gene family might have evolved via recombination between a DNA-binding domain and other functional domains, the MNB1a gene seemed to have no introns in the coding region. These results suggest that a simple exon-shuffling model is not sufficient to explain the molecular evolution of this multigene gene family but that complicated recombination played an important role in the evolution.

Amino Acid Sequence↗

PubMed2002

Multigene family isoform profiling from blood cell lineages.

BACKGROUND: Analysis of cell-selective gene expression for families of proteins of therapeutic interest is crucial when deducing the influence of genes upon complex traits and disease susceptibility. Presently, there is no convenient tool for examining isoform-selective expression for large gene families. A multigene isoform profiling strategy was developed and used to investigate the inwardly rectifying K+ (Kir) channel family in human leukocytes. Comprised of seven subfamilies, Kir channels have important roles in setting the resting membrane potential in excitable and non-excitable cells. RESULTS: Gene sequence alignment allowed determination of "islands" of amino acid homology, and sub-family "centred" priming permitted simultaneous co-amplification of each family member. Validation and cross-priming analysis was performed against a panel of cognate Kir channel clones. Radiolabelling and diagnostic restriction digestion of pooled PCR products enabled determination of distinct Kir gene expression profiles in pure populations of human neutrophils, eosinophils and lung mast cells, with conservation of Kir2.0 isoforms amongst the leukocyte subsets. We also identified a Kir2.0 channel product, which may potentially represent a novel family member. CONCLUSIONS: We have developed a novel, rapid and flexible strategy for the determination of gene family isoform composition in any cell type with the additional capacity to detect hitherto unidentified family members and verified its application in a study of Kir channel isoform expression in human leukocytes.

Journal Article↗