This gene is intronless, arose via retrotransposition of the phosphoglycerate kinase 1 gene, and is expressed specifically in the testis. Initially assumed to be a pseudogene, the encoded protein is actually a functional phosphoglycerate kinase that catalyzes the reversible conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate, during the Embden-Meyerhof-Parnas pathway of glycolysis, in the later stages of spermatogenesis.[provided by RefSeq, May 2010].