This gene encodes a member of the trypsin family of serine proteases. Studies in mouse suggest that the encoded enzyme may be involved in structural reorganizations associated with learning and memory. The enzyme is also expressed in Leydig cells in the testis, but its function in this tissue is unknown. Defects in this gene are a cause of mental retardation autosomal recessive type 1 (MRT1). [provided by RefSeq, Jul 2010].