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Biochim Biophys Acta. 2009 Aug;1793(8):1343-53. doi: 10.1016/j.bbamcr.2009.05.005. Epub 2009 May 21.

HSPB7 is a SC35 speckle resident small heat shock protein.

Author information

  • 1Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Erratum in

  • Biochim Biophys Acta. 2009 Dec;1793(12):1929-30.

Abstract

BACKGROUND:

The HSPB family is one of the more diverse families within the group of HSP families. Some members have chaperone-like activities and/or play a role in cytoskeletal stabilization. Some members also show a dynamic, stress-induced translocation to SC35 splicing speckles. If and how these features are interrelated and if they are shared by all members are yet unknown.

METHODS:

Tissue expression data and interaction and co-regulated gene expression data of the human HSPB members was analyzed using bioinformatics. Using a gene expression library, sub-cellular distribution of the diverse members was analyzed by confocal microscopy. Chaperone activity was measured using a cellular luciferase refolding assay.

RESULTS:

Online databases did not accurately predict the sub-cellular distribution of all the HSPB members. A novel and non-predicted finding was that HSPB7 constitutively localized to SC35 splicing speckles, driven by its N-terminus. Unlike HSPB1 and HSPB5, that chaperoned heat unfolded substrates and kept them folding competent, HSPB7 did not support refolding.

CONCLUSION:

Our data suggest a non-chaperone-like role of HSPB7 at SC35 speckles.

GENERAL SIGNIFICANCE:

The functional divergence between HSPB members seems larger than previously expected and also includes non-canonical members lacking classical chaperone-like functions.

PMID:
19464326
[PubMed - indexed for MEDLINE]
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