Cloning, structure and mRNA expression of human Cctg, which encodes the chaperonin subunit CCTγ

摘要

pWe describe the cloning, DNA sequence analysis and mRNA expression analysis of human Cctg (HsCctg), a gene that encodes the γ-subunit of the eukaryotic cytosolic ‘bc/bhaperonin-bc/bontaining bT/bCP-1’ (CCT). Partial clones representing the 3? region of HsCctg cDNA were isolated from a human kidney cDNA library, and the missing 5? region was amplified directly from human kidney cDNA. The Cctg mRNA transcript is expressed in numerous human and mouse tissues and, like Tcp-1/Ccta, Cctg mRNA is expressed at higher levels in mouse testis when compared with kidney and brain. Southern-blot analysis has also revealed the Cctg gene to be highly conserved in mouse, rat, sheep and frog. The 1901 bp HsCctg cDNA has a coding region of 1635 bp and encodes a predicted 60 kDa protein (544 amino acids). The predicted HsCCTγ amino acid sequence shares a high degree of sequence similarity with γ-subunits from the mouse iMus musculus/i (98% similarity), the yeast iSaccharomyces cerevisiae/i (75% similarity) and the protozoan iTetrahymena pyriformis/i (76% similarity) as well as with other members of the TF55/TCP-1 family, such as human TCP-1/CCTα (55% similarity) and TCP-20/CCTζ (54% similarity). HsCCTγ also shares conserved domains previously identified in the TF55/TCP-1 family of chaperonins and more distantly related chaperonins such as GroEL and Hsp60./p