Calcium-Activated Neutral Proteinase in Myelin: its Role and Function

This chapter briefly describes the features of Calcium-Activated Neutral Proteinase (CANP) found in nonneural tissue and compile the data available concerning the association of CANP with myelin with reference to purification, localization, regulation, role in protein modification, and possible physiological significance. CANP has been implicated in the destruction of muscle in muscular dystrophy and of myelin in both animal experimental spinal cord injury and in MS. CANP absorbed during preparation would be removed during washings and purification of myelin; instead, the specific activity of CANP was increased several fold in purified myelin, suggesting that CANP in myelin is membrane bound. When CANP translocates to the membrane it is believed to bind with the endogenous inhibitor and activator and interact as well with membrane lipids to render it more sensitive to calcium. The increased CANP activity in myelin of developing brain may also be taken as an index of myelination. The myelin mCANP may regulate turnover of CNS proteins.