一个陆地棉羧基末端蛋白酶cDNA的克隆及其表达分析

利用PCR筛选方法从陆地棉纤维cDNA文库中分离出1个基因序列，命名为ChCtp。该cDNA全长1917bp，编码1个含473个氨基酸残基的多肽。GhCtp蛋白与拟南芥和水稻中的一类羧基末端蛋白酶具有较高的同源性，在GhCtp的N-末端有1个精氨酸富集区，而C-末端有1个Pfam数据库中编号为DUF239的高度保守区域；该蛋白的N-末端还存在1个在拟南芥和水稻羧基蛋白酶中所缺乏的ATP/GTP结合区A序列。亲水性分析表明，GhCtp为1个可能的跨膜蛋白。从表达特征来看，GhCtp不属于纤维细胞特异表达或优势表达基因，并且它在棉花不同组织中或不同纤维发育时期的表达强度均很低。

Cloning and Expression Analysis of Carboxyl-terminal Protease cDNA from Gossypium hirsutum L.

A full-length cotton cDNA,designated GhCtp,was isolated from Gossypium hirsutum L.by the PCR-based cDNA library screening.The cDNA encodes a polypeptide of 473-amino acid residues.Sequence alignment showed that GhCtp was highly homo-(logous) to a family of carboxyl-terminal proteases (Ctp) from other species.GhCtp is a potential transmembrane protease,and comprises a conserved domain numbered DUF239 at its carboxyl-terminal and an arginine-rich region at the amino-terminal,respectively.Furthermore,there is a putative ATP-/GTP-binding site motif A (P-loop) in GhCtp which do not exist in Ctps of Arabidopsis and Oryza,indicating that GhCtp might function in a manner different from other Ctps.RT-PCR analysis suggested that GhCtp was not a fiber-specific or -preferential gene,and had a low expression level in different tissues or developmental stages of cotton.