Complete primary sequence of equine cartilage link protein deduced from complementary DNA.
Investigation of the structure of the equine articular cartilage link protein (LP) from individuals ranging in age from 1 to 15 years identified 3 distinct isoforms having molecular weights of 46,000, 43,000 and 41,000. The relative amounts of each of the 3 isoforms altered with age. The largest form did not change with age; however, amounts of the Mr 43,000 and 41,000 forms increased with increasing age. The results suggested that an accumulation, in the extracellular matrix of cartilage, of these 2 smaller products may have arisen from proteolytic cleavage. The complete amino acid sequence of the protein core was determined from complementary DNA products prepared by polymerase chain reaction amplification of cartilage LP mRNA. The sequence had 96% similarity with human LP and with that of other species for which the primary structure has been determined. This high degree of sequence conservation and the isoform data indicate that extracellular processing of LP occurs by similar mechanisms in various species. At the transcription level, equine chondrocytes were found to express LP as 2 abundant mRNA of 5.0 and 3.0 kb, and a smaller mRNA of 1.5 kb. Processing of the LP m RNA in horses, thus, appears to be similar to that found in other species investigated, an although multiple transcripts are present, the coding region remains unaltered and only 1 protein product is made.
Dudhia
J
J
Kennedy Institute of Rheumatology, Hammersmith, London, United Kingdom.
Platt
D
D
D000375:Aging / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002358:Cartilage, Articular / Q000254:growth & development / Q000378:metabolism*; D017931:DNA Primers; D018076:DNA, Complementary; D004591:Electrophoresis, Polyacrylamide Gel; D016326:Extracellular Matrix Proteins; D006736:Horses; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification; D011509:Proteoglycans / Q000096:biosynthesis / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D000099249:Proteoglycan Link Protein
D017931:DNA Primers; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D011506:Proteins; D011509:Proteoglycans; D000099249:Proteoglycan Link Protein