Microfibril-associated glycoprotein-2 interacts with fibrillin-1 and fibrillin-2 suggesting a role for MAGP-2 in elastic fiber assembly.
Elastic fibers are composed of the protein elastin and a network of 10-12 nm microfibrils. The microfibrillar proteins include, among others, the fibrillins and microfibril-associated glycoproteins-1 and -2 (MAGP-1 and MAGP-2). Little is known about how microfibrillar proteins interact to support fiber assembly. We used the C-terminal half of MAGP-2 in a yeast two-hybrid library screen to identify relevant ligands. Six of 13 positive clones encoded known microfibrillar proteins, including fibrillin-1 and -2. Deletion analysis of partial fibrillin-1 and -2 clones revealed a calcium-binding epidermal growth factor repeat-containing region near the C terminus responsible for binding. This region is distinct from the region of fibrillin-1 reported by others to bind MAGP-1. The MAGP-2 bait was unable to interact productively with other epidermal growth factor repeats in fibrillin-1, demonstrating specificity of the interaction. Deletion analysis of the MAGP-2 bait demonstrated that binding occurred in a core region containing 48% identity and 7 conserved cysteine residues with MAGP-1. Immunoprecipitation of MAGP-2 from transfected COS-7 cells resulted in the coprecipitation of fibrillin. These results demonstrate that MAGP-2 specifically interacts with fibrillin-1 and -2 and suggest that MAGP-2 may help regulate microfibrillar assembly. The results also demonstrate the utility of the yeast two-hybrid system to study protein-protein interactions of the extracellular matrix.
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Barnes-Jewish Hospital at Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Akiyo S
AS
Penner
Matthew J
MJ
Rock
Cay M
CM
Kielty
J Michael
JM
Shipley
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000378:metabolism; D003285:Contractile Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D017931:DNA Primers; D004549:Elastin / Q000378:metabolism*; D016326:Extracellular Matrix Proteins; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D008024:Ligands; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D000072260:RNA Splicing Factors; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D054392:Adipokines
D002135:Calcium-Binding Proteins; D003285:Contractile Proteins; D017931:DNA Primers; D004549:Elastin; D016326:Extracellular Matrix Proteins; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D008024:Ligands; D008840:Microfilament Proteins; D000072260:RNA Splicing Factors; C000605724:Fbn1 protein, mouse; D054392:Adipokines; C000605728:Fbn2 protein, mouse; C060820:fibulin; C016598:microfibrillar protein