Interaction between amino propeptides of type XI procollagen alpha1 chains.
Type XI collagen is a quantitatively minor yet essential constituent of the cartilage extracellular matrix. The amino propeptide of the alpha1 chain remains attached to the rest of the molecule for a longer period of time after synthesis than the other amino propeptides of type XI collagen and has been localized to the surface of thin collagen fibrils. Yeast two-hybrid system was used to demonstrate that a homodimer of alpha1(XI) amino propeptide (alpha1(XI)Npp) could form in vivo. Interaction was also confirmed using multi-angle laser light scattering, detecting an absolute weight average molar mass ranging from the size of a monomer to the size of a dimer (25,000-50,000 g/mol), respectively. Binding was shown to be saturable by ELISA. An interaction between recombinant alpha1(XI)Npp and the endogenous alpha1(XI)Npp was observed, and specificity for alpha1(XI)Npp but not alpha2(XI)Npp was demonstrated by co-precipitation. The interaction between the recombinant form of alpha1(XI)Npp and the endogenous alpha1(XI)Npp resulted in a stable association during the regeneration of cartilage extracellular matrix by fetal bovine chondrocytes maintained in pellet culture, generating a protein that migrated with an apparent molecular mass of 50-60 kDa on an SDS-polyacrylamide gel.
Oxford
Julia Thom
JT
Department of Biology, Boise State University, Boise, Idaho 83725, USA. joxford@boiststate.edu
DeScala
Joseph
J
Morris
Nick
N
Gregory
Kate
K
Medeck
Ryan
R
Irwin
Katey
K
Oxford
Rex
R
Brown
Raquel
R
Mercer
Linda
L
Cusack
Sorcha
S
D000818:Animals; D002850:Chromatography, Gel; D024161:Collagen Type XI / Q000737:chemistry / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques
D024161:Collagen Type XI; D011994:Recombinant Proteins