Production and application of a polyclonal peptide antiserum for universal detection of StAR protein.

We report production of a polyclonal antibody against the StAR (steroidogenic acute regulatory) protein of steroidogenic cells and immunohistochemistry (IHC) staining of bovine adrenal gland tissue available in paraffin block. The epitope-specific polyclonal antibody was produced in a rabbit immunized against a synthetic 26 amino acid peptide (82AMQRALGILKDQEGWKKESRANGDE107) derived from the coding sequences reported for the bovine StAR gene (Gene Bank Accession No. Q28918). Western blots were developed using the StAR-specific peptide antiserum with an alkaline-phosphatase-conjugated anti-rabbit IgG second antibody chromogenic system. The antiserum was found to be highly specific for StAR, which exhibited an estimated molecular weight of about 30 KDa for all species analyzed. Finally, the peptide antiserum was successfully employed to localize StAR protein by immunohistochemical staining of thin sections prepared from bovine adrenal gland tissue. This study is the first to report a polyclonal peptide antiserum that apparently recognizes native StAR protein, regardless of the species of origin. The successful production of the antibody has provided a useful tool for studying regulation of StAR protein.