Molecular cloning of human calmitine, a mitochondrial calcium binding protein, reveals identity with calsequestrine.
The cDNA of a mitochondrial calcium binding protein, "calmitine", has been cloned from a human skeletal muscle cDNA library. One cDNA of 1.8 kb has been isolated and sequenced. It encodes for a protein of 390 amino acid residues of 41,746 KDa and contains a leading peptide of 28 amino acids. The sequencing showed the possibility for 21 phosphorylation sites, 4 myristylation sites, and one N glycosylation site. Sequence comparison with other proteins revealed the identity of calmitine with calsequestrine, the sarcoplasmic reticulum low affinity, but high Ca2+ binding capacity, protein isolated in 1971. Subcellular fractionation showed a marked increase in these Ca2+ binding proteins in mitochondria as compared with the sarcoplasmic reticulum; furthermore the mitochondrial matrix is highly enriched with that protein. Therefore, our data either suggest a bicompartimentation of calmitine or indicate that the localization of calsequestrine should be reconsidered in the light of our data. Calmitine represents the Ca2+ reservoir of mitochondria, the function of which could be similar to what has been reported for calsequestrine in the sarcoplasmic reticulum.
Bataille
N
N
U 298 INSERM, CHR Angers, France.
Schmitt
N
N
Aumercier-Maes
P
P
Ollivier
B
B
Lucas-Heron
B
B
Lestienne
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D002155:Calsequestrin / Q000096:biosynthesis* / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D003001:Cloning, Molecular; D015723:Gene Library; D006801:Humans; D051379:Mice; D008931:Mitochondria, Muscle / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D021382:Protein Sorting Signals / Q000737:chemistry; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
C503129:CASQ1 protein, human; D002135:Calcium-Binding Proteins; D002155:Calsequestrin; C503130:Casq1 protein, mouse; D024101:Mitochondrial Proteins; D009838:Oligodeoxyribonucleotides; D021382:Protein Sorting Signals