TCP11 is a testis-specific gene encoding a G protein-coupled receptor involved in male fertility and sperm function. Primarily, TCP11 serves as a probable receptor for fertilization-promoting peptide (FPP) at the sperm membrane, modulating adenylyl cyclase-cAMP signaling pathways essential for sperm capacitation and acrosome reactions 1. TCP11 is expressed exclusively in fertile adult testes, with multiple alternatively spliced isoforms identified in human sperm 2. The protein interacts with outer dense fiber 1 (ODF1), contributing to proper sperm tail morphology and motility 2. TCP11 protein levels are significantly reduced in spermatozoa with abnormal morphology (coiled sperm), indicating its role in determining sperm quality 2. In male infertility contexts, TCP11 has emerged as a biomarker for assessing spermatogenic capacity, with expression ranking among the top five predictive genes (88% accuracy) for testicular function in idiopathic non-obstructive azoospermia 3. TCP11 protein alterations are associated with bilateral varicocele-related infertility 4. High-impact TCP11 variants lacking homozygous mutant genotypes in fertile populations are considered potentially deleterious for stallion fertility 5. Notably, TCP11 also exhibits unexpected tumor-suppressive functions in cervical cancer, where overexpression inhibits proliferation, migration, and promotes apoptosis 6.