TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model.
Sarcoplasmic/endoplasmic reticulum (SR) and nuclear membranes contain two related cation channels named TRIC-A and TRIC-B. In many tissues, both subtypes are co-expressed, making it impossible to distinguish the distinct single-channel properties of each subtype. We therefore incorporated skeletal m...
| Main Authors: | , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2013
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| _version_ | 1797092739399024640 |
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| author | Venturi, E Matyjaszkiewicz, A Pitt, S Tsaneva-Atanasova, K Nishi, M Yamazaki, D Takeshima, H Sitsapesan, R |
| author_facet | Venturi, E Matyjaszkiewicz, A Pitt, S Tsaneva-Atanasova, K Nishi, M Yamazaki, D Takeshima, H Sitsapesan, R |
| author_sort | Venturi, E |
| collection | OXFORD |
| description | Sarcoplasmic/endoplasmic reticulum (SR) and nuclear membranes contain two related cation channels named TRIC-A and TRIC-B. In many tissues, both subtypes are co-expressed, making it impossible to distinguish the distinct single-channel properties of each subtype. We therefore incorporated skeletal muscle SR vesicles derived from Tric-a-knockout mice into bilayers in order to characterise the biophysical properties of native TRIC-B without possible misclassification of the channels as TRIC-A, and without potential distortion of functional properties by detergent purification protocols. The native TRIC-B channels were ideally selective for cations. In symmetrical 210 mM K(+), the maximum (full) open channel level (199 pS) was equivalent to that observed when wild-type SR vesicles were incorporated into bilayers. Analysis of TRIC-B gating revealed complex and variable behaviour. Four main sub-conductance levels were observed at approximately 80 % (161 pS), 60 % (123 pS), 46 % (93 pS), and 30 % (60 pS) of the full open state. Seventy-five percent of the channels were voltage sensitive with Po being markedly reduced at negative holding potentials. The frequent, rapid transitions between TRIC-B sub-conductance states prevented development of reliable gating models using conventional single-channel analysis. Instead, we used mean-variance plots to highlight key features of TRIC-B gating in a more accurate and visually useful manner. Our study provides the first biophysical characterisation of native TRIC-B channels and indicates that this channel would be suited to provide counter current in response to Ca(2+) release from the SR. Further experiments are required to distinguish the distinct functional properties of TRIC-A and TRIC-B and understand their individual but complementary physiological roles. |
| first_indexed | 2024-03-07T03:50:18Z |
| format | Journal article |
| id | oxford-uuid:c101a462-c0a4-4cc0-a22a-8586cc5dd1dd |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:50:18Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | oxford-uuid:c101a462-c0a4-4cc0-a22a-8586cc5dd1dd2022-03-27T05:58:24ZTRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:c101a462-c0a4-4cc0-a22a-8586cc5dd1ddEnglishSymplectic Elements at Oxford2013Venturi, EMatyjaszkiewicz, APitt, STsaneva-Atanasova, KNishi, MYamazaki, DTakeshima, HSitsapesan, RSarcoplasmic/endoplasmic reticulum (SR) and nuclear membranes contain two related cation channels named TRIC-A and TRIC-B. In many tissues, both subtypes are co-expressed, making it impossible to distinguish the distinct single-channel properties of each subtype. We therefore incorporated skeletal muscle SR vesicles derived from Tric-a-knockout mice into bilayers in order to characterise the biophysical properties of native TRIC-B without possible misclassification of the channels as TRIC-A, and without potential distortion of functional properties by detergent purification protocols. The native TRIC-B channels were ideally selective for cations. In symmetrical 210 mM K(+), the maximum (full) open channel level (199 pS) was equivalent to that observed when wild-type SR vesicles were incorporated into bilayers. Analysis of TRIC-B gating revealed complex and variable behaviour. Four main sub-conductance levels were observed at approximately 80 % (161 pS), 60 % (123 pS), 46 % (93 pS), and 30 % (60 pS) of the full open state. Seventy-five percent of the channels were voltage sensitive with Po being markedly reduced at negative holding potentials. The frequent, rapid transitions between TRIC-B sub-conductance states prevented development of reliable gating models using conventional single-channel analysis. Instead, we used mean-variance plots to highlight key features of TRIC-B gating in a more accurate and visually useful manner. Our study provides the first biophysical characterisation of native TRIC-B channels and indicates that this channel would be suited to provide counter current in response to Ca(2+) release from the SR. Further experiments are required to distinguish the distinct functional properties of TRIC-A and TRIC-B and understand their individual but complementary physiological roles. |
| spellingShingle | Venturi, E Matyjaszkiewicz, A Pitt, S Tsaneva-Atanasova, K Nishi, M Yamazaki, D Takeshima, H Sitsapesan, R TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model. |
| title | TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model. |
| title_full | TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model. |
| title_fullStr | TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model. |
| title_full_unstemmed | TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model. |
| title_short | TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model. |
| title_sort | tric b channels display labile gating evidence from the tric a knockout mouse model |
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