Mediates the proteolytic cleavage of HP/haptoglobin in the endoplasmic reticulum.
Highly expressed in placenta, liver, kidney, pancreas, moderately in lung, spleen, prostate, ovary, colon, and PBL, and weakly in heart, skeletal muscle, thymus, testis, and small intestine. Expressed in PC-3 (prostate adenocarcinoma) and SK-OV-3 (ovary adenocarcinoma) cells, but not in LoVo and HT-29 (colon adenocarcinoma), SMMC7721 (hepatocellular carcinoma), CaoV-3 (ovary adenocarcinoma), HeLa (cervix epithelioid carcinoma), MCF-7 (breast adenocarcinoma), U-251MG (glioma) or A-549 (lung carcinoma) cells. Widely expressed in myeloid leukemia cell lines, including K-562 (chronic myelogenous leukemia), THP-1 (myelomonocytic leukemia), HL-60 and NB4 (promyelocytic leukemia), and KG-1 (acute myelogenous leukemia) cells. Expressed mainly in the liver and in serum (at protein level).
Belongs to the peptidase S1 family. Contains 1 CUB domain. Contains 1 peptidase S1 domain.