Cysteine-rich secretory protein 3 (CRISP-3, SGP 28) belongs to the CRISP family of proteins having a PR-1 (pathogenesis related protein 1) domain at its N-terminal and ion channel regulatory (ICR) domain at its C-terminal connected by a hinge region. CRISP-3 transcripts are shown to be present predominantly in the prostate. Its expression is low in benign prostatic epithelium but is highly upregulated in the majority of high-grade prostatic intraepithelial neoplasia lesions and in most primary prostate tumours and metastases. Two independent studies have shown that CRISP-3 is one of the genes that are most often upregulated in prostate cancer. Human Prostate Secretory Protein (PSP94) has been shown to bind human CRISP-3 with very high affinity. Functional significance of this complex is not yet known. Yet, it was suggested, that involvement of the hinge region of CRISPs in interaction with PSP94 may affect the domain movement of CRISPs essential for the ion-channel regulatory activity resulting in inhibition of this activity.