Degradation of purified neurofilament subunits by calcium-activated neutral protease: characterization of the cleavage products.

Neurofilament proteins (NFP) purified from rat spinal cord were labeled with (125)-I and incubated with a crude extract from rat spinal cord containing Ca(2+)-activated protease(s). The protease(s) activated by mM Ca(2+) cleaved the NFP and produced a series of breakdown products which were different for each NFP. The amount of cleavage was dependent upon the incubation time with proteases but the pattern remained constant. Some of the cleavage products were relatively stable. These observations suggest that the cleavage products produced by treating NFP subunits with the endogenous protease can be used as a finger print to further study NFP metabolism and to better understand their role in physiological and pathological conditions of the nervous system.