Sperm Associated Antigen 11A (SPAG11A)

Defensins are short, processed peptide molecules that are classified into three different structural groups: alpha-defensins, beta-defensins and theta-defensins. Much interest has been focused on the genetic variation in defensin loci present in the human population, as this may be a key in understanding individual differences in disease susceptibility and severity. The defensin genes are located on 8p23-p22.Also of interest is the SPAG11A gene, which is located about 17 kb upstream from the defensin genes. SPAG11A encodes for proteins with an antibacterial activity which affect sperm maturation. The SPAG11A gene is 19 kb long - including 3 kb of proximal promoter region - and contains 8 exons and 2 promoters. It is thought that SPAG11A is derived from ancestral beta-defensin genes.