Identification and characterization of PRKCBP1, a candidate RACK-like protein

The receptors for activated C-kinase (RACK) family of proteins function as anchors for activated protein kinase C (PKC) isoenzymes. Using a monoclonal antibody to RACK1 in the screening of a human hippocampus cDNA library, we identified a novel member of the RACK family, designated PRKCBP1. Immunopr ecipitation assays performed with a GST-fused PRKCBP1 protein suggest the c arboxy terminus of PRKCBP1 interacts specifically with PKC beta 1. Northern analysis detected a 3.1-kb PRKCBP1 transcript in all tissues examined incl uding brain, heart, liver, lung, pancreas, skeletal muscle, kidney, and spl een. The PRKCBP1 gene has been localized to human Chromosome (Chr) 20q12-13 .1. Several groups have reported evidence for genetic linkage of Type II di abetes to this region in Caucasian families. This localization, combined wi th the observation that abnormalities in the activation, translocation, and inhibition of PRC occur in the development of Type II diabetes, suggested that PRKCBP1 was a candidate for contributing to Type II diabetes. We deter mined the PRKCBP1 coding sequence is 1845 bp in length, dispersed over 9 ex ons, spanning approximately 34 kb of genomic DNA. SSCP analysis was used to screen PRKCBP1 coding regions for mutations or polymorphisms in 100 Caucas ian Type II diabetics and 100 Caucasian unaffected individuals. A silent C/ T transition (bp1413, Thr137) was present in 23% of both diabetic and contr ol individuals. A C/T transition (bp198) was also identified in a single di abetic individual, which resulted in no coding change (Ser66). The results of this analysis suggest that PRKCBP1 coding variations are uncommon and do not contribute to Type TI diabetes in the general population.