IDENTIFICATION AND PURIFICATION OF A CHICKEN BRAIN NEUROGLIA-ASSOCIATED PROTEIN

The identification, purification, and biochemical characterization of specific markers for neuroglial cells in the central nervous system is an essential step toward a better understanding of the function of gl ial cells. This manuscript reports the identification and purification of a neuroglia-associated protein (NAP-185) with an apparent molecula r mass of 185 kDa. While its expression is not restricted to the brain , it was first identified in a specific subpopulation of glial cells w hen chick brain stem sections were analyzed with an affinity-purified rabbit antiserum raised against the catalytic domain of the T-cell pro tein tyrosine phosphatase. This 185-kDa antigen was purified to appare nt homogeneity and confirmed to be responsible for the neuroglial stai ning observed. In spite of its immunological relation to T-cell protei n tyrosine phosphatase, purified NAP-185 failed to display tyrosine ph osphatase activity. The primary sequence of five NAP-185-derived pepti des shows that this protein has not yet been characterized and that it is possibly related to AP180, a clathrin-associated protein.