The SPEF2 gene encodes a sperm flagellar protein 2 that exists in four isoforms. Isoform 1 is 1,822 amino acids long at 209 kDA, isoform 2 is 1,818 amino acids long at 209 kDA, isoform 3 is 514 amino acids long at 61 kDA, and isoform 4 is 619 amino acids long at 70 kDA. The protein encoded by the SPEF2 gene is thought to be critical to correct axoneme development. This gene interacts with genes APOA1 and IGHA1. SPEF2 has been linked to diseases such as primary ciliary dyskinesia and infertility.
