Sperm lysozyme-like protein 1 (SLLP1)

Sperm lysozyme-like protein 1 (SLLP1) is a non-bacteriolytic c-type lysozyme-like protein specifically localized in the acrosome of human spermatozoa. Unlike traditional lysozymes, SLLP1 lacks catalytic activity due to mutations in key active site residues, but it plays a critical role in fertilization by mediating the interaction between the sperm and the oocyte plasma membrane. It specifically binds to the oocyte surface receptor SASB1, facilitating sperm-egg recognition and adhesion. Beyond its role in reproduction, SLLP1 is classified as a cancer/testis antigen because it is ectopically expressed in various malignancies, including lung and breast cancers, while being restricted to the testis in healthy tissues. This restricted expression pattern and its essential role in fertilization make SLLP1 a promising target for the development of non-hormonal contraceptives and targeted cancer immunotherapies.

Other names

Lysozyme-like protein 1Lysozyme-c-like protein 1LYC1Cancer/testis antigen 146CT146

Potential contraceptive vaccines or small molecule inhibitors could target SLLP1 to block sperm-egg binding and prevent fertilization.