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 homologous 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.