ANNEXIN-1 IS PRESENT IN DIFFERENT MOLECULAR-FORMS IN RAT CEREBRAL-CORTEX

Previously we have purified annexin 1 [J. Neurochem. 56 (1991) 1985-19 86] from pig cerebral cortex as a monomeric protein of 37 kDa. Here, t he localization of annexin 1 was investigated in subcellular fractiona tions of rat cerebral cortex using immunodetection by a specific antib ody. In contrast to synaptophysin, a specific synaptic vesicle integra l membrane protein, annexin 1 is located in the synaptic plasma membra ne fraction where it appears on SDS-PAGE as a polypeptide of 74 kDa. A nnexin 1 is extracted also as a 74 kDa polypeptide from the purified s ynaptic plasma membranes. These results suggest for the 74 kDa molecul ar form an enzymatic dimerization of annexin 1 when associated to the membrane.