Identity of the 155 ATPase with the Eukarvotic Mg"'-Arpase and Its Immunoreactivitv to the 26S protease Complex from Chick Skeletal Muscle

15S ATPase와 진핵세포에 존재하는 Mg2+-ATPase의 동질성 및 계 골격근에서 분리된 26S 단백질 분해효소와의 면역반응에 관한 연구

Partial internal amino acid sequences of the 15S ATPase from chick skeletal muscle were determined and found to be identical to the corresponding regions of the Mg2+_ATPase from Xenopus laevis oocytes, that is a close homolog of N-ethvlmaleimide-sensitive factor (called NSF) in hamster and Sec18p in yeast, both of which are believed to plaN an essential role in vesicle fusion in secretory process. Thus, the 15S Arpase in chick skeletal muscle maw also belong to a protein family of the "vesicle fusion proteins". Unlike the Mg2'-Afpase with an isoelectric point (pl) of 5.5, however, the 15S Arpase was separated into four spots with pls of 4.9,6.4 and 6.9 upon analysis by twoiimensional gel electrophoresis. In addition, the anti-15S ATPase IgG was found to be capable of interacting with the 265 protease complex upon analysis by immunoprecipitation. Moreover, immunoblot analysis revealed that the anti-155 Arpase IgG recognizes three subunits, ko of which show the same mobilities as the 510-kDa subunit 4 and 48-kDa subunit 7 of the 26S protease complex that are known to contain a highly consented ATP-binding motif. These results surest that a common antigenic site, likely the consensus nucleotide-binding site, exists in the 15S ATPase and the 26S pretense complex and hence both the enzymes maw also be related ATPases.d ATPases.