Surfeit locus gene homologs are widely distributed in invertebrate genomes.
The mouse Surfeit locus contains six sequence-unrelated genes (Surf-1 to -6) arranged in the tightest gene cluster so far described for mammals. The organization and juxtaposition of five of the Surfeit genes (Surf-1 to -5) are conserved between mammals and birds, and this may reflect a functional or regulatory requirement for the gene clustering. We have undertaken an evolutionary study to determine whether the Surfeit genes are conserved and clustered in invertebrate genomes. Drosophila melanogaster and Caenorhabditis elegans homologs of the mouse Surf-4 gene, which encodes an integral membrane protein associated with the endoplasmic reticulum, have been isolated. The amino acid sequences of the Drosophila and C. elegans homologs are highly conserved in comparison with the mouse Surf-4 protein. In particular, a dilysine motif implicated in endoplasmic reticulum localization of the mouse protein is conserved in the invertebrate homologs. We show that the Drosophila Surf-4 gene, which is transcribed from a TATA-less promoter, is not closely associated with other Drosophila Surfeit gene homologs but rather is located upstream from sequences encoding a homolog of a yeast seryl-tRNA synthetase protein. There are at least two closely linked Surf-3/rpL7a genes or highly polymorphic alleles of a single Surf-3/rpL7a gene in the C. elegans genome. The chromosomal locations of the C. elegans Surf-1, Surf-3/rpL7a, and Surf-4 genes have been determined. In D. melanogaster the Surf-3/rpL7a, Surf-4, and Surf-5 gene homologs and in C. elegans the Surf-1, Surf-3/rpL7a, Surf-4, and Surf-5 gene homologs are located on completely different chromosomes, suggesting that any requirement for the tight clustering of the genes in the Surfeit locus is restricted to vertebrate lineages.
Armes
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Eukaryotic Gene Organization and Expression Laboratory, Imperial Cancer Research Fund, London, United Kingdom.
Fried
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D017124:Conserved Sequence; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D017344:Genes, Insect; D008040:Genetic Linkage; D016678:Genome; D008565:Membrane Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012714:Serine-tRNA Ligase / Q000737:chemistry; D014158:Transcription, Genetic
D029742:Caenorhabditis elegans Proteins; D029721:Drosophila Proteins; D008565:Membrane Proteins; D015345:Oligonucleotide Probes; D012269:Ribosomal Proteins; C489186:RpL7A protein, Drosophila; C489187:Rpl7a protein, mouse; C486260:Surf4 protein, Drosophila; C486258:sft-4 protein, C elegans; D012714:Serine-tRNA Ligase