Molecular and functional analyses of aspolin, a fish-specific protein extremely rich in aspartic acid.
Aspolin is a muscular protein having unique structural characteristics where the most part of its primary structure is occupied by aspartic acid. Aspolin has been found exceptionally in fish muscle, suggesting its specific role in this tissue. However, biological functions of aspolin have remained unknown. In the present study, we cloned full-length cDNAs encoding zebrafish Danio rerio aspolins 1 and 2, revealed their genomic organization, and examined in vivo function using knockdown techniques. Genomic analysis clearly showed that aspolin is a paralog of the histidine-rich calcium binding protein gene, which encodes a calcium binding protein in sarcoplasmic reticulum (SR). Expression analysis showed that the transcripts and their translated products, aspolins 1 and 2, are distributed in myotomal skeletal muscle, but not in cardiac muscle. Injection of antisense morpholino oligo targeting both aspolins 1 and 2 increased the mRNA levels of calsequestrin 1, another calcium binding protein in SR. These lines of evidence suggest that aspolins regulate calcium concentrations in SR.
Kinoshita
Shigeharu
S
Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo, Tokyo, 113-8657, Japan.
Katsumi
Eriko
E
Yamamoto
Hiroshi
H
Takeuchi
Kazuharu
K
Watabe
Shugo
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D040461:Gene Components; D055785:Gene Knockdown Techniques; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D010802:Phylogeny; D020161:Physical Chromosome Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015027:Zebrafish
D002135:Calcium-Binding Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D009124:Muscle Proteins; C068969:HRC protein, human