Regulation of fibrillin carboxy-terminal furin processing by N-glycosylation, and association of amino- and carboxy-terminal sequences.
The molecular mechanisms of fibrillin assembly into microfibrils are poorly understood. In this study, we investigated human fibrillin-1 carboxy-terminal processing and assembly using a recombinant approach. Processing of carboxy-terminal fibrillin-1 was strongly influenced by N-glycosylation at the site immediately downstream of the furin site, and by association with calreticulin. The carboxy terminus of fibrillin-2 underwent less efficient processing than carboxy-terminal fibrillin-1 under identical conditions. Size fractionation of the amino-terminal region of fibrillin-1, and of unprocessed and furin-processed carboxy-terminal region of fibrillin-1, revealed that the amino terminus formed abundant disulphide-bonded aggregates. Some association of unprocessed carboxy-terminal fibrillin-1 was also apparent, but processed carboxy-terminal sequences remained monomeric unless amino-terminal sequences encoded by exons 12-15 were present. These data indicate the presence of fibrillin-1 molecular recognition sequences within the amino terminus and the extreme carboxy-terminal sequence downstream of the furin site, and a specific amino- and carboxy-terminal association which could drive overlapping linear accretion of furin-processed fibrillin molecules in the extracellular space. Differences in processing of the two fibrillin isoforms may reflect differential abilities to assemble in the extracellular space.
Ashworth
J L
JL
Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences and Department of Medicine, University of Manchester M13 9PT, UK.
Kelly
V
V
Rock
M J
MJ
Shuttleworth
C A
CA
Kielty
C M
CM
D004721:Endoplasmic Reticulum / Q000378:metabolism; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D045683:Furin; D006031:Glycosylation; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism / Q000494:pharmacology; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D013381:Subtilisins / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D054392:Adipokines
D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D045683:Furin; D008840:Microfilament Proteins; D018832:Molecular Chaperones; D013381:Subtilisins; C000605722:FBN1 protein, human; D054392:Adipokines; C000605723:FBN2 protein, human