Endoplasmic Reticulum Golgi Intermediate Compartment Protein 2 (ERGIC2)

ERGIC2 has a calculated molecular mass of 42.6 kD. It contains an N-terminal nuclear localization signal, 2 N-glycosylation sites, and multiple phosphorylation sites. RT-PCR analysis detected ubiquitous expression of PTX1 in human tissues. Immunoblot analysis detected recombinant PTX1 as a 73-kD protein in both nuclear and cytoplasmic extracts of normal human prostate, with much higher levels in nuclear extracts. The high apparent molecular mass was likely due to glycosylation. Immunohistochemical analysis identified PTX1 mainly in nuclei of glandular epithelia of normal prostate and muscle cells. Nuclear expression of PTX1 was greatly reduced in prostate cancer, and the reduction was greater in advanced prostate cancer compared with early prostate cancer.