title: Origin and evolution of gene for prolactin-induced protein.
abstract: Prolactin-induced protein (PIP) is a small protein secreted into the fluid in several glands. We determined the PIP coding sequences of 5 hominoid species and estimated the numbers of synonymous and nonsynonymous substitutions for each branch of the mammalian PIP gene tree. The branch connecting hominoids and Old World monkeys showed significantly higher nonsynonymous than synonymous substitutions. These changes tended to be accumulated in the fibronectin-binding domain. Many other primate branches also showed higher nonsynonymous than synonymous substitutions, thus suggesting that the PIP genes of primates have experienced some kind of positive selection. We also considered the phylogenetic relationship of the PIP gene with the alpha-2-macroglobulin gene family. The results indicate that the PIP gene arose by partial gene duplication from a member of the alpha-2-macroglobulin gene family after the divergence between amphibians and other tetrapods.
authors.affiliation: Department of Experimental and Forensic Pathology, Yamagata University School of Medicine, 2-2-2 Iidanishi, Yamagata 990-9585, Japan. tkitano@med.id.yamagata-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Kitano
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.forename: Kazuo
authors.initials: K
authors.lastname: Umetsu
authors.forename: Isao
authors.initials: I
authors.lastname: Yuasa
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Naruya
authors.initials: N
authors.lastname: Saitou
authors.forename: Motoki
authors.initials: M
authors.lastname: Osawa
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics*; D004247:DNA / Q000235:genetics; D019143:Evolution, Molecular; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D011323:Primates / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D000511:alpha-Macroglobulins / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D006023:Glycoproteins; D026901:Membrane Transport Proteins; C488892:PIP protein, human; D000511:alpha-Macroglobulins; D004247:DNA