Puromycin Sensitive Aminopeptidase (PSA)

This puromycin-sensitive aminopeptidase, a zinc metallopeptidase which hydrolyzes amino acids from the N-terminus of its substrate. The protein has been localized to both the cytoplasm and to cellular membranes. This enzyme degrades enkaphalins in the brain, and studies in mouse suggest that it is involved in proteolytic events regulating the cell cycle.PSA contains a zinc-binding motif conserved among gluzincin aminopeptidases and shares 98% sequence identity with the mouse protein. Northern blot analysis detected ubiquitous expression of a 4.8-kb transcript, with highest expression in brain. By in situ hybridization of adult human brain sections, expression was localized to the perikaryon of neurons of the cortex and cerebellum.