THE LOCALIZATION OF AN ANTIBODY TO STEP IN EMBRYONIC STRIATAL TISSUE GRAFTS

WE used immunohistochemical staining with antibodies against the novel protein striatal enriched phosphatase (STEP) to investigate the inter nal organization of grafts of embryonic striatal tissues implanted in the ibotenic acid-lesioned neostriatum of adult rats. STEP immunoreact ivity was found in discrete patches within the grafts, which colocaliz ed with areas designated as 'patch' zones when stained for the enzyme acetylcholinesterase and with antibodies against tyrosine hydroxylase and DARPP-32. As previously hypothesized, the pattern of STEP immunore activity in embryonic striatal tissue grafts provides further indicati on that the patch zones are indeed comprised of striatal like cell pop ulations. The novel protein STEP provides a sensitive and precise mark er for this compartment within the grafts.