Secreted Epididymal Glycoprotein: DISCUSSION(9)

Sequence Analysis of 2D6 Antigen and Preliminary Assignment of Functionality

As mentioned earlier, a sequence analysis of the 24-kDa subunit purified from cauda spermatozoa revealed that it is identical to isoantigen E-2 and that it belongs to a family of small epididymal peptides, 68 to 123 residues long, that show significant sequence similarity to somatic p-defensins. The defensins are a family of cationic antimicrobial peptides with a broad spectrum of activity, which, together with several other families of antimicrobial peptides, such as the cathelicidins, lactoferrin, and lysozyme, make up an important component of the innate immune system. ethinyl estradiol

Two principal families of defensins have been described: a-defensins, which are expressed by neutrophils, and p-defensins, which are produced by epithelial cells. Both types of defensins possess antimicrobial activity and seem to play a role in the bridging of the responses of the innate and adaptive immune systems by activating receptors on dendritic and T cells. They contain a central conserved cysteine-rich core domain but differ in the pattern of disulfide bonding within that region. Genome analysis has suggested that there are many more defensin-like proteins present in mammals than previously suspected. In human, 31 genes have been identified that encode proteins with defensin-like motifs.