This gene encodes a member of the the glycogenin family. Glycogenin is a self-glucosylating protein involved in the initiation reactions of glycogen biosynthesis. A gene on chromosome 3 encodes the muscle glycogenin and this X-linked gene encodes the glycogenin mainly present in liver; both are involved in blood glucose homeostasis. This gene has a short version on chromosome Y, which is 3' truncated and can not make a functional protein. Multiple alternatively spliced transcript variants encoding different isoforms have been identified.[provided by RefSeq, May 2010].