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The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions

STBD1 (starch-binding domain-containing protein 1) belongs to the CBM20 (family 20 carbohydrate binding module) group of proteins, and is implicated in glycogen metabolism and autophagy. However, very little is known about its regulation or interacting partners. Here, we show that the CBM20 of STBD1...

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Autores principales: Zhu, Yuanqi, Zhang, Mei, Kelly, Amber Renee, Cheng, Alan
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Portland Press Ltd. 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076837/
https://www.ncbi.nlm.nih.gov/pubmed/24837458
http://dx.doi.org/10.1042/BSR20140053
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author Zhu, Yuanqi
Zhang, Mei
Kelly, Amber Renee
Cheng, Alan
author_facet Zhu, Yuanqi
Zhang, Mei
Kelly, Amber Renee
Cheng, Alan
author_sort Zhu, Yuanqi
collection PubMed
description STBD1 (starch-binding domain-containing protein 1) belongs to the CBM20 (family 20 carbohydrate binding module) group of proteins, and is implicated in glycogen metabolism and autophagy. However, very little is known about its regulation or interacting partners. Here, we show that the CBM20 of STBD1 is crucial for its stability and ability to interact with glycogen-associated proteins. Mutation of a conserved tryptophan residue (W293) in this domain abolished the ability of STBD1 to bind to the carbohydrate amylose. Compared with the WT (wild-type) protein, this mutant exhibited rapid degradation that was rescued upon inhibition of the proteasome. Furthermore, STBD1 undergoes ubiquitination when expressed in COS cells, and requires the N-terminus for this process. In contrast, inhibition of autophagy did not significantly affect protein stability. In overexpression experiments, we discovered that STBD1 interacts with several glycogen-associated proteins, such as GS (glycogen synthase), GDE (glycogen debranching enzyme) and Laforin. Importantly, the W293 mutant of STBD1 was unable to do so, suggesting an additional role for the CBM20 domain in protein–protein interactions. In HepG2 hepatoma cells, overexpressed STBD1 could associate with endogenous GS. This binding increased during glycogenolysis, suggesting that glycogen is not required to bridge this interaction. Taken together, our results have uncovered new insights into the regulation and binding partners of STBD1.
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spelling pubmed-40768372014-07-11 The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions Zhu, Yuanqi Zhang, Mei Kelly, Amber Renee Cheng, Alan Biosci Rep Original Paper STBD1 (starch-binding domain-containing protein 1) belongs to the CBM20 (family 20 carbohydrate binding module) group of proteins, and is implicated in glycogen metabolism and autophagy. However, very little is known about its regulation or interacting partners. Here, we show that the CBM20 of STBD1 is crucial for its stability and ability to interact with glycogen-associated proteins. Mutation of a conserved tryptophan residue (W293) in this domain abolished the ability of STBD1 to bind to the carbohydrate amylose. Compared with the WT (wild-type) protein, this mutant exhibited rapid degradation that was rescued upon inhibition of the proteasome. Furthermore, STBD1 undergoes ubiquitination when expressed in COS cells, and requires the N-terminus for this process. In contrast, inhibition of autophagy did not significantly affect protein stability. In overexpression experiments, we discovered that STBD1 interacts with several glycogen-associated proteins, such as GS (glycogen synthase), GDE (glycogen debranching enzyme) and Laforin. Importantly, the W293 mutant of STBD1 was unable to do so, suggesting an additional role for the CBM20 domain in protein–protein interactions. In HepG2 hepatoma cells, overexpressed STBD1 could associate with endogenous GS. This binding increased during glycogenolysis, suggesting that glycogen is not required to bridge this interaction. Taken together, our results have uncovered new insights into the regulation and binding partners of STBD1. Portland Press Ltd. 2014-07-01 /pmc/articles/PMC4076837/ /pubmed/24837458 http://dx.doi.org/10.1042/BSR20140053 Text en © 2014 The Author(s) This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC-BY) (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. http://creativecommons.org/licenses/by/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC-BY) (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Paper
Zhu, Yuanqi
Zhang, Mei
Kelly, Amber Renee
Cheng, Alan
The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions
title The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions
title_full The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions
title_fullStr The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions
title_full_unstemmed The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions
title_short The carbohydrate-binding domain of overexpressed STBD1 is important for its stability and protein–protein interactions
title_sort carbohydrate-binding domain of overexpressed stbd1 is important for its stability and protein–protein interactions
topic Original Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076837/
https://www.ncbi.nlm.nih.gov/pubmed/24837458
http://dx.doi.org/10.1042/BSR20140053
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