TAILIEUCHUNG - Báo cáo khoa học: In vivo heteromer formation. Expression of soluble bA4-crystallin requires coexpression of a heteromeric partner

Theb-crystallins are a family of long-lived, abundant structural proteins that are coexpressed in the vertebrate lens. As b-crystallins form hetero-mers, a process that involves transient exposure of hydrophobic interfaces, we have examined whetherin vivo b-crystallin assembly is enhanced by pro-tein chaperones, either small heat shock proteins, Hsp27 or aB-crystallin, or Hsp70. | iFEBS Journal In vivo heteromer formation. Expression of soluble pA4-crystallin requires coexpression of a heteromeric partner Laura Marin-Vinader1 Carla Onnekink1 Siebe T. van Genesen1 Christine Slingsby2 and Nicolette H. Lubsen1 1 Department of Biochemistry Radboud University Nijmegen The Netherlands 2 Department of Crystallography Birkbeck College London UK Keywords aB-crystallin b-crystallin cataract chaperones hsp27 Correspondence N. H. Lubsen Department of Biochemistry 271 Radboud University Nijmegen PO Box 9101 6500 HB Nijmegen The Netherlands Fax 31 24 3540525 Tel 31 24 3616850 E-mail Received 14 March 2006 revised 16 May 2006 accepted 18 May 2006 doi The b-crystallins are a family of long-lived abundant structural proteins that are coexpressed in the vertebrate lens. As b-crystallins form heteromers a process that involves transient exposure of hydrophobic interfaces we have examined whether in vivo b-crystallin assembly is enhanced by protein chaperones either small heat shock proteins Hsp27 or aB-crystallin or Hsp70. We show here that bA4-crystallin is abundantly expressed in HeLa cells but rapidly degraded irrespective of the presence of Hsp27 aB-crystallin or Hsp70. Degradation is even enhanced by Hsp70. Coexpression of bA4-crystallin with bB2-crystallin yielded abundant soluble bA4 bB2-crystallin heteromers bB1-crystallin was much less effective in solubilizing bA4-crystallin. As bB2-crystallin competed for bA4-crystallin with Hsp70 and the proteasomal degradation pathway bB2-crystallin probably captures an unstable bA4-crystallin intermediate. We suggest that the proper folding of bA4-crystallin is not mediated by general chaperones but requires a heteromeric partner which then also acts as a dedicated chaperone towards bA4-crystallin. A major hurdle in making a functional protein is folding 1 2 . Proteasome inhibition studies have revealed that a significant fraction of the newly made protein .

• Báo cáo khoa học
• Report medicine
• traditional medicine
• scientific reports
• breast cancer
• biological activities
• gastric cancer
• medical knowledge
• medical research
• analysis of cytoplasmic
• oxidation
• Crystal structure
• bacteria
• hemoglobin
• medicine
• cell proliferation
• chemical reaction
• hormone medicine
• tumor cells
• biochemical studies
• environmental medicine