A novel isoform of delta-sarcoglycan is localized at the sarcoplasmic reticulum of mouse skeletal muscle.
The sarcoglycan-sarcospan complex (alpha-, beta-, gamma-, delta-, epsilon-, and zeta-SG-SSPN), a component of the dystrophin-associated glycoprotein complex (DAGC), is located at the sarcolemma of muscle fibers where it contributes to maintain cell integrity during contraction-relaxation cycles; gamma- and delta-SG are also expressed in the sarcoplasmic reticulum (SR). In this study, we report the identification of a novel isoform of murine delta-SG produced by alternative splicing that we named delta-SG3. This isoform is present at transcript level in several tissues, with its highest expression in skeletal and cardiac muscle. The delta-SG3 protein lacks the last 122 amino acids at the C-terminal, which are replaced by 10 new amino acids (EGFLNMQLAG). Interestingly, double immunofluorescence analysis for delta-SG3 and the dihydropyridine receptor (DHPR) shows a close localization of these two proteins. We propose the subcellular distribution of this novel delta-SG3 isoform at the SR and its involvement in intracellular calcium concentration regulation.
Estrada
Francisco J
FJ
Unidad de Investigación Médica en Genética Humana, Hospital de Pediatría, Centro Médico Nacional Siglo XXI-IMSS, Av. Cuauhtémoc 330, Col. Doctores, C.P. 06725 México, DF, Mexico.
Mornet
Dominique
D
Rosas-Vargas
Haydeé
H
Angulo
Alexandra
A
Hernández
Manuel
M
Becker
Viola
V
Rendón
Alvaro
A
Ramos-Kuri
Manuel
M
Coral-Vázquez
Ramón M
RM
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000737:chemistry; D002352:Carrier Proteins / Q000737:chemistry; D002460:Cell Line; D016189:Dystrophin / Q000378:metabolism; D005091:Exons; D006023:Glycoproteins / Q000737:chemistry; D007438:Introns; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D049031:Sarcoglycans / Q000737:chemistry*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D020746:Calcium Channels, L-Type; D002352:Carrier Proteins; D016189:Dystrophin; D006023:Glycoproteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D010455:Peptides; D020033:Protein Isoforms; D012333:RNA, Messenger; C109646:SSPN protein, human; D049031:Sarcoglycans; D002118:Calcium