Age-related increase in a cathepsin D like protease that degrades brain microtubule-associated proteins.

摘要: In microtubules isolated from brains of very old rats, two the major microtubule-associated proteins, MAP1 and MAP2, are found only in degraded form. is present as a piece whose molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis circa 50,000 smaller than native protein, MAP2 extensively fragmented. The forms both proteins tissue homogenates but rapidly during microtubule isolation. proteolytic activity responsible for this degradation cathepsin D like, being more active at acid pH neutral completely blocked by pepstatin 10(-7) M. Fractionation aged brain supernatant permeation chromatography showed that degrading elutes with single peak like activity. known to promote assembly, their protease levels increase age could be related defective assembly which occur age-related degenerative conditions such Alzheimer's disease.