Identification of triadin 1 as the predominant triadin isoform expressed in mammalian myocardium

Yvonne M. Kobayashi, Larry Jones

Research output: Contribution to journalArticle

77 Citations (Scopus)

Abstract

Triadin is an integral membrane protein of sarcoplasmic reticulum shown to interact with the ryanodine receptor/Ca2+ release channel, junctin, and calsequestrin. Several triadin isoforms have been postulated to exist in cardiac muscle, but to date none has been conclusively identified. Here, we show that only triadin 1 is significantly expressed. We cloned and sequenced cDNAs encoding canine cardiac triadin 1 and 3 but found no evidence for triadin 2. From deduced primary structures, antibodies against domains common to all triadins and an antibody against the unique C terminus of triadin 1 were raised. All antibodies detected two prominent proteins of molecular masses 35 and 40 kDa on immunoblots from cardiac microsomes, including the antibody that recognizes only triadin 1. The 40-kDa mobility form was shown to correspond to the glycosylated form of triadin 1, not a distinct triadin 2 isoform as previously hypothesized. Confirming this, overexpression of triadin 1 in transgenic mouse hearts produced both the 35-kDa deglycosylated and the 40-kDa glycosylated mobility forms. The glycosylation site of triadin 1 was localized to asparagine residue 75, and its bitopic arrangement in the membrane was confirmed. Although a 92-kDa immunoreactive protein could be tentatively identified in myocardium as triadin 3, its expression level was insignificant (≤5%) compared with that of triadin 1. We conclude that triadin 1 is the triadin isoform most likely to play a role in Ca2+ release in heart.

Original languageEnglish
Pages (from-to)28660-28668
Number of pages9
JournalJournal of Biological Chemistry
Volume274
Issue number40
DOIs
StatePublished - Oct 1 1999

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Myocardium
Protein Isoforms
Antibodies
triadin
Calsequestrin
Glycosylation
Ryanodine Receptor Calcium Release Channel
Asparagine
Molecular mass
Sarcoplasmic Reticulum
Microsomes
Transgenic Mice
Muscle
Canidae
Membrane Proteins
Proteins
Complementary DNA
Membranes

ASJC Scopus subject areas

  • Biochemistry

Cite this

Identification of triadin 1 as the predominant triadin isoform expressed in mammalian myocardium. / Kobayashi, Yvonne M.; Jones, Larry.

In: Journal of Biological Chemistry, Vol. 274, No. 40, 01.10.1999, p. 28660-28668.

Research output: Contribution to journalArticle

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