Methionine aminopeptidase II: A molecular chaperone for sarcoplasmic reticulum calcium ATPase.
The monoclonal antibody to the beta-subunit of H(+)/K(+)-ATPase (mAbHKbeta) cross-reacts with a protein that acts as a molecular chaperone for the structural maturation of sarcoplasmic reticulum (SR) Ca(2+)-ATPase. We partially purified a mAbHKbeta-reactive 65-kDa protein from Xenopus ovary. After in-gel digestion and peptide sequencing, the 65-kDa protein was identified as methionine aminopeptidase II (MetAP2). The effects of MetAP2 on SR Ca(2+)-ATPase expression were examined by injecting the cRNA for MetAP2 into Xenopus oocytes. Immunoprecipitation and pulse-chase experiments showed that MetAP2 was transiently associated with the nascent SR Ca(2+)-ATPase. Synthesis of functional SR Ca(2+)-ATPase was facilitated by MetAP2 and prevented by injecting an antibody specific for MetAP2. These results suggest that MetAP2 acts as a molecular chaperone for SR Ca(2+)-ATPase synthesis.
Noguchi
Shunsuke
S
Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka 820-8502, Japan.
Komiya
Tohru
T
Eguchi
Hiroshi
H
Shirahata
Akira
A
Nikawa
Jun-ichi
J
Kawamura
Masaru
M
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D005260:Female; D047468:Immunoprecipitation; D063208:Methionyl Aminopeptidases; D008845:Microinjections; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D011485:Protein Binding; D018075:RNA, Complementary / Q000008:administration & dosage / Q000235:genetics; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D018832:Molecular Chaperones; D018075:RNA, Complementary; D000626:Aminopeptidases; D063208:Methionyl Aminopeptidases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases