Histone-like protein Protamine 1 (gene: PRM1) is visualized in the late stage cell states of developing sperm in testis with multiplex immunohistochemistry (mIHC/IF).

The mIHC/IF spermatids panel is designed for high resolution spatial localization in the various cell states of late stage spermatogenesis in testis. Using this panel, protamine 1 (PRM1) is localized (green) to the nucleus 'head' of spermatids with elongating (red) or elongated (white) tail, while not present in different states of round spermatids (magenta and cyan). DNA condensation with protamine, a substitute to histone proteins in developing sperm, results in more densely packed and inactive DNA compared with histones. Protamine is also known for its use as an inhibitor of the anticoagulant heparin.

The spatial expression pattern of PRM1 is validated by single-cell RNA sequencing data which shows highly enriched expression in late spermatids.

For more details about the mIHC/IF technique visit our method page.