The Human Cysteine‐Rich Secretory Protein (CRISP) Family

We report the isolation and characterisation of cDNAs encoding three different, human members of the cysteine‐rich secretory protein (CRISP) family. The novel CRISP‐I exists in five cDNA subtypes differing by the presence or absence of a stretch coding for a C‐terminal cysteine‐rich domain so far found in all members of the family, and by the length of their 3‐untranslated region. CRISP‐2 cDNA corresponds to the previously described TPXI form, with so far unreported 5′‐untranslated sequence heterogeneities while CRISP‐3 cDNA codes for a new, unique protein. Northern blot analysis of various human organs indicates that CRISP‐1 transcripts are epididymis‐specific whereas CRISP‐2/TPXI transcripts are detected mainly in the testis and also in the epididymis. CRISP‐3 transcripts are more widely distributed and found predominantly in the salivary gland, pancreas and prostate, and in less abundance in the epididymis, ovary, thymus and colon. A protein reacting with an anti‐mouse CRISP‐1 antibody was isolated from human epididymal extracts and N‐terminal sequencing revealed that it corresponded to the CRISP‐1 cDNA we have isolated. In contrast to findings on its rat counterpart epididymal protein DE/acidic epididymal glycoprotein (AEG), no significant association of CRISP‐1 with human spermatozoa was observed.