cDNA clone to chick corneal chondroitin/dermatan sulfate proteoglycan reveals identity to decorin.
A 1.6-kb cDNA clone was isolated by screening a library prepared from chick corneal mRNA with a cDNA clone to bovine decorin. The cDNA contained an open reading frame coding for a M(r) 39,683 protein. A 19-amino-acid match with sequence from the N-terminus of core protein from the corneal chondroitin/dermatan sulfate proteoglycan confirmed the clone as a corneal proteoglycan and the homology with human and bovine decorin confirmed its identity as decorin. Structural features of the deduced sequence include a 16-amino-acid signal peptide, a 14-amino-acid propeptide, cysteine residues at the N- and C-terminal regions, and a central leucine-rich region (comprising 63% of the protein) containing nine repeats of the sequence LXXLXLXXNXL/I. Chick decorin contains three variations of this sequence that are tandemly linked to form a unit and three units tandemly linked to form the leucine-rich region. The presence of beta bend amino acids flanking the units may serve to delineate the units as structural elements of the leucine-rich region. Sequence homology within the repeats and the spacing of the repeats suggest that this region arose by duplication. Chick decorin primarily differs from mammalian decorins in the 19-amino-acid sequence that starts the N-terminus of the core protein. Within this region, the serine that serves as a potential acceptor for the chondroitin/dermatan sulfate side chain is preceded by a glycine instead of being followed by a glycine as it is in the mammalian decorins and all other mammalian proteoglycans.
Li
W
W
Department of Ophthalmology, Eye and Ear Institute of Pittsburgh, University of Pittsburgh School of Medicine, Pennsylvania 15213.
Vergnes
J P
JP
Cornuet
P K
PK
Hassell
J R
JR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002645:Chickens; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics*; D003001:Cloning, Molecular; D003315:Cornea / Q000502:physiology*; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D058575:Decorin; D003871:Dermatan Sulfate / Q000235:genetics*; D016326:Extracellular Matrix Proteins; D015723:Gene Library; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D011509:Proteoglycans / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid
D011508:Chondroitin Sulfate Proteoglycans; C546878:DCN protein, human; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; C032649:dermatan sulfate proteoglycan; D003871:Dermatan Sulfate; D004247:DNA