The human gene (PCOLCE) for the C-proteinase enhancer, a glycoprotein that enhances the enzymatic activity that cleaves the type I procollagen C-propeptide, was previously mapped to the same cytogenetic region (7q21.3-q22) as COL1A2, the type I collagen pro-alpha 2 chain gene. The apparent proximity of these two genes, whose products interact, might have reflected some mechanism for coregulation of expression. We have employed somatic cell hybrids, cosmid contigs, and interspecific backcross mice to investigate further the apparent proximity of the two genes. Our data show that PCOLCE and CO1A2 are separated by at least 6 Mb on human chromosome 7q and that Pcolce and Col1a2 are located on two separate chromosomes in mouse, These data also indicate that PCOLCE is located within a 10- to 15-cM region of conserved synteny between human chromosome 7 and mouse chromosome 5. (C) 1996 Academic Press, Inc.