The microfibrillar proteins MAGP-1 and fibrillin-1 form a ternary complex with the chondroitin sulfate proteoglycan decorin.
MAGP-1 and fibrillin-1, two protein components of extracellular microfibrils, were shown by immunoprecipitation studies to interact with the chondroitin sulfate proteoglycan decorin in the medium of cultured fetal bovine chondrocytes. Decorin interacted with each protein individually and with both proteins together to form a ternary complex. Expression of truncated fibrillin-1 proteins in Chinese hamster ovary cells localized proteoglycan binding to an amino-terminal region near the proline-rich domain. A spatially analogous fibrillin-2 truncated protein did not coprecipitate the same sulfated molecule, suggesting that chondroitin sulfate proteoglycan binding in this region is specific for fibrillin-1. An interaction between fibrillin and MAGP-1 was also observed under culture conditions that abrogated decorin secretion, suggesting that the two microfibrillar proteins can associate in the absence of the proteoglycan. Sulfation of matrix proteins is important for elastic fiber assembly because inhibition of sulfation was shown to prevent microfibrillar protein incorporation into the extracellular matrix of cultured cells.
Trask
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BC
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Trask
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Broekelmann
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Mecham
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RP
D000818:Animals; D016466:CHO Cells / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D011232:Chemical Precipitation; D002704:Chlorates / Q000494:pharmacology; D019902:Chondrocytes / Q000187:drug effects / Q000648:ultrastructure; D002809:Chondroitin Sulfates / Q000737:chemistry; D003285:Contractile Proteins / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D003470:Culture Media; D058575:Decorin; D004547:Elastic Tissue / Q000166:cytology / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000378:metabolism; D016326:Extracellular Matrix Proteins; D000071837:Fibrillins; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism*; D000072260:RNA Splicing Factors; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D002704:Chlorates; D003285:Contractile Proteins; D003470:Culture Media; D058575:Decorin; D016326:Extracellular Matrix Proteins; D000071837:Fibrillins; D008840:Microfilament Proteins; D010446:Peptide Fragments; D011509:Proteoglycans; D000072260:RNA Splicing Factors; D011994:Recombinant Proteins; C016598:microfibrillar protein; D002809:Chondroitin Sulfates