AKAP3 (A-kinase anchoring protein 3) is a structural component of the sperm fibrous sheath that plays a critical role in male fertility 1. The protein is essential for sperm flagellum structure formation, sperm motility, and male fertility by serving as a scaffolding protein that anchors protein kinase A to the fibrous sheath via the regulatory subunit of the kinase 2. AKAP3 functions through multiple mechanisms including protein-protein interactions, forming complexes with other fibrous sheath proteins such as CABYR and Ropporin 3. The protein undergoes tyrosine phosphorylation, which is crucial for sperm motility regulation, particularly when stimulated by bicarbonate through soluble adenylate cyclase activation 4. Additionally, AKAP3 is phosphorylated by STK33, which regulates fibrous sheath assembly during spermiogenesis 5. Disease relevance includes spermatogenic failure, as homozygous deleterious variants in AKAP3 cause multiple morphological abnormalities of sperm flagella (MMAF) and asthenoteratozoospermia 1. Clinical significance is demonstrated by the finding that AKAP3 expression levels may influence intracytoplasmic sperm injection (ICSI) treatment outcomes, with dosage-dependent effects on prognosis 1. The protein also interacts with other spermatogenic proteins like CEP135, contributing to proper flagellar development 6.