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Complete primary sequence of equine cartilage link protein deduced from complementary DNA
American Journal of Veterinary Research
|July 1, 1995
Summary
Equine articular cartilage link protein (LP) shows age-related changes in isoform abundance, with smaller forms increasing. This suggests proteolytic cleavage and similar processing mechanisms across species for this conserved protein.
Area of Science:
- Biochemistry
- Molecular Biology
- Veterinary Science
Background:
- Articular cartilage is a complex tissue crucial for joint function.
- Link protein (LP) is a key component of cartilage extracellular matrix, influencing its structural integrity.
- Understanding age-related changes in cartilage components is vital for addressing joint diseases.
Purpose of the Study:
- To investigate the structure and age-related expression of equine articular cartilage link protein (LP).
- To determine the amino acid sequence of the equine LP core protein and compare it with other species.
- To analyze the mRNA transcripts of LP in equine chondrocytes.
Main Methods:
- Analysis of LP isoforms in equine cartilage from horses aged 1 to 15 years using molecular weight determination.
- Determination of the complete amino acid sequence of the LP core protein via complementary DNA (cDNA) products from polymerase chain reaction (PCR) amplification of LP mRNA.
- Analysis of LP mRNA transcripts in equine chondrocytes using techniques to identify different mRNA sizes.
Main Results:
- Identified three distinct LP isoforms (46,000, 43,000, and 41,000 Mr) in equine cartilage.
- Observed an age-dependent increase in the relative amounts of the 43,000 and 41,000 Mr LP isoforms, suggesting accumulation possibly due to proteolytic cleavage.
- Determined the equine LP core protein sequence, revealing 96% similarity to human LP and high conservation across species.
- Identified two abundant LP mRNA transcripts (5.0 and 3.0 kb) and a smaller one (1.5 kb) in equine chondrocytes, indicating similar mRNA processing to other species.
Conclusions:
- Equine articular cartilage LP undergoes age-related changes in isoform composition.
- Proteolytic processing of LP appears to be conserved across different species.
- Equine chondrocytes express LP via multiple mRNA transcripts, but the coding region remains consistent, leading to a single protein product.