Molecular cloning and expression of cDNA encoding a lumenal calcium binding glycoprotein from sarcoplasmic reticulum.
Antibody screening was used to isolate a cDNA encoding the 160-kDa glycoprotein of rabbit skeletal muscle sarcoplasmic reticulum. The cDNA is identical to that encoding the 53-kDa glycoprotein except that it contains an in-frame insertion of 1308 nucleotides near its 5' end, apparently resulting from alternative splicing. The protein encoded by the cDNA would contain a 19-residue NH2-terminal signal sequence and a 453-residue COOH-terminal sequence identical to the 53-kDa glycoprotein. It would also contain a 436-amino acid insert between these sequences. This insert would be highly acidic, suggesting that it might bind Ca2+. The purified 160-kDa glycoprotein and the glycoprotein expressed in COS-1 cells transfected with cDNA encoding the 160-kDa glycoprotein were shown to bind 45Ca2+ in a gel overlay assay. The protein was shown to be located in the lumen of the sarcoplasmic reticulum and to be associated through Ca2+ with the membrane. We propose that this lumenal Ca2+ binding glycoprotein of the sarcoplasmic reticulum be designated "sarcalumenin."
Banting and Best Department of Medical Research, Charles H. Best Institute, University of Toronto, ON, Canada.
E
E
Leberer
J H
JH
Charuk
N M
NM
Green
D H
DH
MacLennan
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002135:Calcium-Binding Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D006023:Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D011817:Rabbits; D015183:Restriction Mapping; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D014158:Transcription, Genetic
D002135:Calcium-Binding Proteins; D006023:Glycoproteins; D012333:RNA, Messenger; D004247:DNA