The procollagen C-proteinase enhancer (PCPE) is a glycoprotein that potentiates enzymatic cleavage of the type I procollagen C-propeptide by bone morphogenetic protein-1 (BMP-1). The human PCPE gene (PCOLCE) was previously mapped to 7q22, an area frequently disrupted in uterine leiomyomata, while disruption of the rat PCPE gene leads to anchorage-independent growth and loss of contact inhibition in rat fibroblasts. Here we describe the entire intron/exon organizations ofPCOLCEand the mouse PCPE gene (Pcolce) and analyze expression ofPCOLCERNA in various human adult and fetal tissues and ofPcolceRNA at various stages of mouse development.PCOLCEandPcolceare shown to be small genes 6.0 and 6.5 kb, respectively, with a conserved intron/exon structure comprising 9 exons. A notable difference between the two genes derives from insertion of multipleAlusequences immediately upstream and downstream and withinPCOLCE.Temporal expression of PCPE mRNA is shown to differ from that of BMP-1 and type I procollagen during mouse development, consistent with possible additional functions for PCPE beyond enhancement of C-proteinase activity. Consistent with a possible role in leiomyomata,PCOLCEis shown to be expressed at relatively high levels in uterus.