Proteomic analysis of human prostasomes.

Prostasomes are secretory particles in human seminal fluid. Other than a microscopic description of these secretory particles and an incomplete two-dimensional gel electrophoresis (2DE) study, little is known about the composition of proteins in prostasomes. We employed a direct iterative approach using Gas phase fractionation and microcapillary HPLC-tandem mass spectrometry (microLC-MS/MS) to catalogue the prostasome proteome. We identified 139 proteins that can be divided into the following categories: (1). enzymes (33.8% of total), (2). transport/structural (19.4% of total), (3). GTP proteins (14.4% of total), (4). chaperone proteins (5.8% of total), (5). signal transduction proteins (17.3% of total), and (6). unannotated proteins (9.4% of total). A total of 128 of the 139 proteins have not previously been described as prostasomal. The proteins identified can be used as reference dataset in future work comparing prostasome proteins between normal and pathological states such as prostate cancer, benign prostatic hyperplasia, prostatitis, and infertility.