Localisation of the C1q binding site within C1q receptor/calreticulin.
C1q receptor (C1qR/collectin receptor) is located on many cell types. Binding of C1q to these cells elicits numerous responses. Protein sequencing has shown that C1qR is almost identical to calreticulin (CaR), an abundant multifunctional protein. Radioiodinated C1qR and CaR bind to C1q with identical characteristics. Three recombinant C1qR/CaR domains (N-, C-terminal domains and central P-domain) were expressed using the Thiofusion system, and used to study the interaction with C1q. Both the N- and P-domains were implicated in C1q binding. A region, termed the S-domain, spanning the N and P intersection was expressed, and showed concentration-dependent binding to C1q, demonstrating that the C1q binding site lies within this region.
Stuart
G R
GR
MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, UK.
Lynch
N J
NJ
Lu
J
J
Geick
A
A
Moffatt
B E
BE
Sim
R B
RB
Schwaeble
W J
WJ
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D037282:Calreticulin; D003094:Collagen / Q000378:metabolism; D003167:Complement Activation; D015922:Complement C1q / Q000378:metabolism*; D006461:Hemolysis; D008562:Membrane Glycoproteins; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011951:Receptors, Complement / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry / Q000378:metabolism*; D012756:Sheep
D002135:Calcium-Binding Proteins; D037282:Calreticulin; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D011951:Receptors, Complement; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; C032402:complement 1q receptor; D015922:Complement C1q; D003094:Collagen