Analysis of fish ZP1/ZPB homologous genes--evidence for both genome duplication and species-specific amplification models of evolution.
The vertebrate egg envelope is composed of a family of related proteins, the zona pellucida (ZP) proteins, which are characterized by the presence of a conserved zona pellucida domain. Analysis of teleost fish ZP gene sequences has demonstrated that there are no direct orthologues of the mammalian ZPB and ZP1 genes, but that teleost fish contain multiple copies of two classes of genes (ZPXa and ZPXb) that are equally related to ZPB and ZP1. The two classes of genes are further distinguished by expression in liver or ovary, respectively, indicating there was probably an initial duplication event, followed by a switch to hepatic expression of one of the paralogues. This switch was followed in some species by additional amplification of one of the paralogues with the subsequent loss of the other. It is proposed that the expansion of the number of ZPXa and ZPXb genes and the acquisition of dual sites of synthesis are the result of an ancient polyploidization event, followed by additional species-specific gene amplifications.
Conner
S J
SJ
Reproductive Biology and Genetics Group, Division of Medical Science, Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TH, UK. s.j.conner@bham.ac.uk
Hughes
D C
DC
D000818:Animals; D004527:Egg Proteins / Q000235:genetics; D019143:Evolution, Molecular; D005260:Female; D029941:Fish Proteins / Q000235:genetics*; D005399:Fishes / Q000235:genetics*; D005784:Gene Amplification; D020440:Gene Duplication; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics; D011956:Receptors, Cell Surface; D016415:Sequence Alignment; D017385:Sequence Homology; D013045:Species Specificity; D000072216:Zona Pellucida Glycoproteins
D004527:Egg Proteins; D029941:Fish Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C000606514:ZP1 protein, human; C082833:ZP4 protein, human; D000072216:Zona Pellucida Glycoproteins