Localization of the receptor-binding site in the collectin family of proteins.
Collectin receptor (Clq receptor) has been shown to bind human Clq, mannose-binding protein (MBP), lung surfactant protein A (SP-A) and bovine conglutinin. These ligands have a similar ultrastructure, each consisting of collagenous and globular domains, but do not show a high degree of sequence similarity. For Clq and SP-A, it has been shown that both bind to cell-surface-expressed receptor(s) via their collagenous regions and this is likely to be the case with the other ligands. Within the collagenous region, near the 'bend' region of the collagen triple helix in Clq, MBP and SP-A, a cluster of similar charged residues is observed. This region has been suggested to be associated with receptor binding. A similar region of charge density occurs close to the N-terminus of conglutinin. In this paper we describe a truncated form of conglutinin, which has 55 amino acids missing from the N-terminus and does not bind to the collectin receptor. The results presented here strongly indicate that receptor-ligand interaction is mediated via the N-terminal region of conglutinin, consistent with the earlier proposal for the binding site.
Malhotra
R
R
Department of Biochemistry, University of Oxford, U.K.
Laursen
S B
SB
Willis
A C
AC
Sim
R B
RB
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D037222:Collectins; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D018960:Hyaluronan Receptors; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D011663:Pulmonary Surfactants / Q000378:metabolism*; D011951:Receptors, Complement / Q000302:isolation & purification / Q000378:metabolism*; D012712:Serum Globulins / Q000378:metabolism*
C087299:C1QBP protein, human; D002352:Carrier Proteins; D037222:Collectins; D018960:Hyaluronan Receptors; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011663:Pulmonary Surfactants; D011951:Receptors, Complement; D012712:Serum Globulins; C032402:complement 1q receptor; C024014:conglutinin