STEP Proteins and Enzymes

The protein tyrosine phosphatase non-receptor type 5 or striatum-enriched protein-tyrosine phosphatase (STEP) protein is part of a family of protein tyrosine phosphatases enriched within the CNS, and is a key component of the NMDAR complex. It is expressed within dopaminoceptive neurons in the CNS and particularly enriched within the basal ganglia and related structures. STEP61 is the membrane-associated isoform and STEP46 is the cytosolic protein. In response to transient hypoxia-ischemia in the brain, STEP61 is proteolytically cleaved by calpain, thereby releasing a smaller isoform, STEP33.