Hyaluronan And Proteoglycan Link Protein 1 (HAPLN1)

Cartilage link protein stabilizes aggregates of aggrecan and hyaluronan, giving cartilage its tensile strength and elasticity. Cartilage provides the template for endochondral ossification and is crucial for determining the length and width of the skeleton. During endochondral bone formation, hypertrophic chondrocytes die and the cartilage is replaced with bone matrix. The deduced amino acid sequence is 354 residues long and shows a striking degree of similarity to porcine, rat, and chicken link protein sequences. By in situ hybridization, they mapped the gene to 5q13-q14.1. CRTL1 gene comprises 5 exons and is spread over more than 60 kb. Primer extension and S1 nuclease protection analysis revealed transcription initiation to be 315 bases upstream from the translation initiation codon.