HLA Complex P5 (HCP5)

The major histocompatibility complex (MHC) is a genomic region on chromosome 6p21.3 that is characterized by the presence of many duplicated gene families. By screening various tissues and cell lines with probes derived from an MHC class I YAC, Vernet et al. (1993) detected a 2.5-kb mRNA transcript in B-cell lines, NK cell lines, activated T cells, and normal spleen. Low stringency probing of genomic DNA revealed multiple copies of a sequence, which the authors termed P5, clustered near HLA-A. One member of the multicopy gene family, designated P5-1, encodes a 219-amino acid protein. Transcription of P5-1 is restricted to lymphoid tissues. Avoustin et al. (1994) determined that P5-1 cDNA represents a chimeric transcript in which the first exon of an HLA class I gene has fused to an unrelated sequence.