TRiC is a cytoplasmic chaperonin involved in actin and tubulin folding. It is formed by six to nine different but related proteins of 52 to 65 kDa arranged in two hetero-oligomeric rings. We have cloned the gene coding for the mouse TRiC-P5 subunit (also called CCT gamma) using a XbaI-DraIII fragment of the mTRiC5 cDNA. The mouse genome contains one TRiC5 gene and one TRiC5 pseudogene located on chromosomes 3F and 5B, respectively. The 2-kb transcript of TRiC5 is encoded by 14 exons distributed within 25 kb of genomic DNA. The largest exon is 312 bp and the smallest exon is 51 bp. We have used primer extension to demonstrate multiple transcription start points for the TRiC5 gene. This is consistent with the lack of any obvious TATA box upstream of the transcription start points.