Distributional and developmental variations of multiple forms of calpastatin in mouse brain

DEAE-cellulose chromatography of mouse brain extract demonstrated the occurrence of two calpastatin fractions, CS-0.1 and CS-0.2, with distinctly higher content of the latter. CS-0.1 emerged from the column at 0.1 M NaCl, inhibited calpain II more strongly than calpain I, and identified also immunologically with hitherto known calpastatin. CS-0.2 emerged at 0.2 M NaCl, inhibited calpain I more strongly than calpain II, and did not crossreact with anti-calpastatin antibody used. Fairly consistent amounts of CS-0.2 and calpain II were found in the brain of mice from 10 days to 10 weeks after birth, while CS-0.1 became measurable only after 4-week growth. In adult mice, CS-0.1 was highest in specific activity in brainstem, lower in cerebellum, and not detectable in cerebral hemisphere. Physiological significance of multiple forms of calpastatin and their variations found is not known.