Abstract
Several key proteins have been localized to junctional sarcoplasmic reticulum which are important for Ca2+ release. These include the ryanodine receptor, triadin, and calsequestrin, which may associate into a stable complex at the junctional membrane. We recently purified and cloned a fourth component of this complex, junctin, which exhibits homology with triadin and is the major 125I-calsequestrin-binding protein detected in cardiac sarcoplasmic reticulum vesicles (Jones, L. R., Zhang, L., Sanborn, K., Jorgensen, A. O., and Kelley, J. (1995) J. Biol. Chem. 270, 30787-30796). In the present study, we have examined the binding interactions between the cardiac forms of these four proteins with emphasis placed on the role of junctin. By a combination of approaches including calsequestrin-affinity chromatography, filter overlay, immunoprecipitation assays, and fusion protein binding analyses, we find that junctin binds directly to calsequestrin, triadin, and the ryanodine receptor. This binding interaction is localized to the lumenal domain of junctin, which is highly enriched in charged amino acids organized into 'KEKE' motifs. KEKE repeats are also found in the common lumenal domain of triadin, which likewise is capable of binding to calsequestrin and the ryanodine receptor (Guo, W., and Campbell, K. P. (1995) J. Biol. Chem. 270, 9027-9030). It appears that junctin and triadin interact directly in the junctional sarcoplasmic reticulum membrane and stabilize a complex that anchors calsequestrin to the ryanodine receptor. Taken together, these results suggest that junctin, calsequestrin, triadin, and the ryanodine receptor form a quaternary complex that may be required for normal operation of Ca2+ release.
| Original language | English |
|---|---|
| Pages (from-to) | 23389-23397 |
| Number of pages | 9 |
| Journal | Journal of Biological Chemistry |
| Volume | 272 |
| Issue number | 37 |
| DOIs | |
| State | Published - 1997 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Complex formation between junctin, triadin, calsequestrin, and the ryanodine receptor : Proteins of the cardiac junctional sarcoplasmic reticulum membrane. / Zhang, Lin; Kelley, Jeff; Schmeisser, Glen; Kobayashi, Yvonne M.; Jones, Larry.
In: Journal of Biological Chemistry, Vol. 272, No. 37, 1997, p. 23389-23397.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Complex formation between junctin, triadin, calsequestrin, and the ryanodine receptor
T2 - Proteins of the cardiac junctional sarcoplasmic reticulum membrane
AU - Zhang, Lin
AU - Kelley, Jeff
AU - Schmeisser, Glen
AU - Kobayashi, Yvonne M.
AU - Jones, Larry
PY - 1997
Y1 - 1997
N2 - Several key proteins have been localized to junctional sarcoplasmic reticulum which are important for Ca2+ release. These include the ryanodine receptor, triadin, and calsequestrin, which may associate into a stable complex at the junctional membrane. We recently purified and cloned a fourth component of this complex, junctin, which exhibits homology with triadin and is the major 125I-calsequestrin-binding protein detected in cardiac sarcoplasmic reticulum vesicles (Jones, L. R., Zhang, L., Sanborn, K., Jorgensen, A. O., and Kelley, J. (1995) J. Biol. Chem. 270, 30787-30796). In the present study, we have examined the binding interactions between the cardiac forms of these four proteins with emphasis placed on the role of junctin. By a combination of approaches including calsequestrin-affinity chromatography, filter overlay, immunoprecipitation assays, and fusion protein binding analyses, we find that junctin binds directly to calsequestrin, triadin, and the ryanodine receptor. This binding interaction is localized to the lumenal domain of junctin, which is highly enriched in charged amino acids organized into 'KEKE' motifs. KEKE repeats are also found in the common lumenal domain of triadin, which likewise is capable of binding to calsequestrin and the ryanodine receptor (Guo, W., and Campbell, K. P. (1995) J. Biol. Chem. 270, 9027-9030). It appears that junctin and triadin interact directly in the junctional sarcoplasmic reticulum membrane and stabilize a complex that anchors calsequestrin to the ryanodine receptor. Taken together, these results suggest that junctin, calsequestrin, triadin, and the ryanodine receptor form a quaternary complex that may be required for normal operation of Ca2+ release.
AB - Several key proteins have been localized to junctional sarcoplasmic reticulum which are important for Ca2+ release. These include the ryanodine receptor, triadin, and calsequestrin, which may associate into a stable complex at the junctional membrane. We recently purified and cloned a fourth component of this complex, junctin, which exhibits homology with triadin and is the major 125I-calsequestrin-binding protein detected in cardiac sarcoplasmic reticulum vesicles (Jones, L. R., Zhang, L., Sanborn, K., Jorgensen, A. O., and Kelley, J. (1995) J. Biol. Chem. 270, 30787-30796). In the present study, we have examined the binding interactions between the cardiac forms of these four proteins with emphasis placed on the role of junctin. By a combination of approaches including calsequestrin-affinity chromatography, filter overlay, immunoprecipitation assays, and fusion protein binding analyses, we find that junctin binds directly to calsequestrin, triadin, and the ryanodine receptor. This binding interaction is localized to the lumenal domain of junctin, which is highly enriched in charged amino acids organized into 'KEKE' motifs. KEKE repeats are also found in the common lumenal domain of triadin, which likewise is capable of binding to calsequestrin and the ryanodine receptor (Guo, W., and Campbell, K. P. (1995) J. Biol. Chem. 270, 9027-9030). It appears that junctin and triadin interact directly in the junctional sarcoplasmic reticulum membrane and stabilize a complex that anchors calsequestrin to the ryanodine receptor. Taken together, these results suggest that junctin, calsequestrin, triadin, and the ryanodine receptor form a quaternary complex that may be required for normal operation of Ca2+ release.
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UR - http://www.scopus.com/inward/citedby.url?scp=0030770826&partnerID=8YFLogxK
U2 - 10.1074/jbc.272.37.23389
DO - 10.1074/jbc.272.37.23389
M3 - Article
VL - 272
SP - 23389
EP - 23397
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 37
ER -