Distribution of Nsp100 and Nsp100 Kinase, a Nerve Growth Factor–Sensitive Phosphorylation System, in Rat Tissues

Previous work from this laboratory has shown that in PC12 cells the phosphorylation of a specific soluble protein is decreased by nerve growth factor treatment. The protein, designated Nsp100, and its kinase have been separated and partially purified from PC12 cells. In the present work, the tissue distribution of Nsp100 phosphorylation in 5-day-old and adult rats was studied. In adult rats, phosphorylation of an Nsp100-like protein was observed in brain, adrenal gland, testis, and muscle, but not in liver or kidney. In 5-day-old rats, a similar phosphorylation was observed in brain, adrenal gland, superior cervical ganglia, liver, spleen, kidney, and muscle. In PC12 cells, Nsp100 phosphorylation is completely inhibited by 5 X 10(-5) M Zn2+ and is completely inactivated by treatment at 50 degrees C for 2 min. The phosphorylation of the Nsp100-like protein in both adult and 5-day-old rats showed the same characteristics. Partial purification of Nsp100 and Nsp100 kinase from the brains of 5-day-old rats was carried out using the procedures developed for PC12 cells. Nsp100 and Nsp100 kinase were separated on diethylaminoethyl-Sephacel, and the kinase was eluted with 0.3 M NaCl; the same results have previously been obtained with PC12 cells. Phosphorylated Nsp100 from brain and from PC12 cells was compared by proteolysis on sodium dodecyl sulfate gels; similar peptide patterns were generated from the two samples.(ABSTRACT TRUNCATED AT 250 WORDS)