Molecular Evolution Of Keratin Associated Protein Genes Family And TSPEAR Gene Of Mammalian

Two human KAP gene families (KAP10 and KAP12) were found in the intron of the TSPEAR (C21ofC29) gene, which were located chromosome 21q22.3 by researching evolution of the keratin associated protein (KAP). In this study, chromosome mapping of KAP 10, KAP12 and TSPEAR gene from eight mammals were constructed at different stages of mammalian evolution. The results suggest that KAP10 and KAP12 gene families were not only located the same chromosome with TSPEAR gene, but also the distance between them is gradually narrowing and they have a trend to enter the introns of TSPEAR. The KAP gene cluster and TSPEAR gene is adjacent on chromosomes of Platypus, opossums and rats, KAP10-11 and KAP10-12 gene of mouse already had entered intron 1 of TSPEAR gene, KAP10-2, KAP10-3, KAP10-4 and KAP10-5 of the dog entered intron 10 of TSPEAR gene, KAP10-2, KAP10-3 and KAP10-4 of the horse located the intron 14 of TSPEAR gene, KAP10 and KAP12 gene families of human and bovine all entered intron 11 and intron 12 of TSPEAR gene.Mammals KAP10 changes in the number of family members more than the number of family members KAP12. This accounted for a sufficient number of KAP10 is essential to keep the mammalian hair growing. KAP12 family numbers have changed greatly in different species, even completely degraded to Platypus. Cysteine content of KAP10 and KAP12 gene families in mammalian are between 16%～30%, so they both belong to high cysteine/ul- tra-high cysteine family. In addition, KAP12 gene family changes in GC% content more obviously than KAP10 in mammalians owing to that it have a greater impact by environment or other factors.Phylogenetic tree analysis showed that KAP10 gene family is divided into three major branches: human, rat and mouse to form a branch; dogs, horses and bovine in the formation of a branch; opossum is an independent branch. Although the experiments do not belong to the phylogenetic tree rooted tree, but it still very clear that KAP10 genes of Platypus is obviously located in the old position. The phenomena that obvious species crosscutting does not exist in phylogenetic tree of KAP10 gene family suggested that it is a young gene family because the evolution of this gene family occurred after the evolution of species. KAP12 gene family phylogenetic tree shows that a lot of crosscutting between the dog, horse and opossum, it shows that gene differentiation is earlier than species evolution. A similar evolution order between genes and species also is found in the amino acids phylogenetic tree of TSPEAR gene.Through analysis the position where mammalian KAP10 and KAP12 genes inserted intron of TSPEAR gene, some findings were as follows. First, a conservative sequence is existed in 3'and 5'exon of TSPEAR gene, which is inserted foreign gene. Second, it is also conservative that sequence of intron of TSPEAR gene and the first KAP gene which inserted the former. Third, AG appeared at 5'and GT at 3'. It just reversed the splice site of intron. This suggested that the intron in TSPEAR gene takes the inserted KAP gene as its intron and their express with different mechanism. Study on molecular evolution of mammalians KAP gene families and TSPEAR gene provide new evidence for the evolution of mammalians intron and hair's structural gene.