Presland R B, Whitbread L A, Rogers G E
Department of Biochemistry, University of Adelaide, South Australia.
J Mol Biol. 1989 Oct 20;209(4):561-76. doi: 10.1016/0022-2836(89)90594-9.
We describe the isolation and characterization of a set of overlapping cosmid clones that contain chicken keratin genes. The 100 kb (1 kb = 10(3) base-pairs) of DNA represented in these clones contains a cluster of 18 feather keratin genes spanning 53 kb of DNA. The feather keratin genes are spaced about 3 kb apart and at least 11 of them have the same transcriptional orientation. Southern analysis using oligonucleotide probes made from highly conserved portions of the 5' non-coding, intron and 3' non-coding regions, respectively, indicate that these sequences have been highly conserved among the gene family as a whole, with only one or two exceptions in each case. The presence of some regularly repeated restriction enzyme sites are indicative of tandem duplication events in the recent history of the feather keratin gene family. The feather keratin gene locus is flanked on both sides by related types of keratin genes. On the 5' side of the feather gene cluster are three keratin genes (designated feather-like) that are located 5 kb from the last feather keratin gene and are spaced about 4 kb apart. On the 3' side of the feather gene cluster, 21 kb from the last feather keratin gene, lies a cluster of four genes that encode claw keratins. These genes are spaced about 1 kb apart and appear to be divergently transcribed. Partial DNA sequence analysis of the feather-like gene lying proximal to the feather keratin gene cluster demonstrated that it encodes a protein of 115 amino acid residues that is 80% homologous to the feather keratins at both the DNA and amino acid sequence levels. The feather-like gene(s) are expressed in both embryonic and adult (post-hatch) chick feathers and at a very low level in embryonic scale tissue. These genes therefore form a new family of feather proteins that is distinct from the previously characterized feather keratins.
我们描述了一组包含鸡角蛋白基因的重叠黏粒克隆的分离和特性分析。这些克隆中所代表的100 kb（1 kb = 10³个碱基对）DNA包含一个由18个羽毛角蛋白基因组成的簇，跨越53 kb的DNA。羽毛角蛋白基因彼此间隔约3 kb，其中至少11个具有相同的转录方向。分别使用由5'非编码区、内含子和3'非编码区的高度保守部分制成的寡核苷酸探针进行的Southern分析表明，这些序列在整个基因家族中高度保守，每种情况下仅有一两个例外。一些规则重复的限制酶切位点的存在表明在羽毛角蛋白基因家族的近期历史中发生了串联重复事件。羽毛角蛋白基因位点两侧是相关类型的角蛋白基因。在羽毛基因簇的5'侧有三个角蛋白基因（称为类羽毛基因），它们距离最后一个羽毛角蛋白基因5 kb，彼此间隔约4 kb。在羽毛基因簇的3'侧，距离最后一个羽毛角蛋白基因21 kb处，有一个由四个编码爪角蛋白的基因组成的簇。这些基因彼此间隔约1 kb，似乎是反向转录的。对位于羽毛角蛋白基因簇近端的类羽毛基因进行的部分DNA序列分析表明，它编码一种由115个氨基酸残基组成的蛋白质，在DNA和氨基酸序列水平上与羽毛角蛋白的同源性均为80%。类羽毛基因在胚胎期和成年（孵化后）鸡的羽毛中均有表达，在胚胎鳞片组织中的表达水平非常低。因此，这些基因形成了一个与先前鉴定的羽毛角蛋白不同的新的羽毛蛋白家族。
