Chemical and hydrodynamic characterization of the human leucocyte receptor for complement subcomponent C1q.
A procedure for preparation of the receptor for complement subcomponent Clq from human tonsil lymphocytes and the monocytic cell line U937 was developed. The procedure is suitable for isolation of several hundred micrograms of the receptor, Clq-R, and has yielded sufficient material for chemical and hydrodynamic characterization. Clq-R from tonsil lymphocytes behaves identically with that from U937 cells. Clq-R has a monomer Mr of 56,000, and is an acidic glycoprotein containing about 17% carbohydrate. The polypeptide chain length is estimated to be 416-448 amino acid residues, with two or three sites for N-linked glycosylation. Detergent-solubilized Clq-R exists as an elongated dimer (f/fo = 1.8), and does not bind a significant weight of detergent. The radioiodinated isolated receptor binds specifically and saturably to solid-phase Clq, but not to collagen, IgG, bovine serum albumin or complement component C3.
Malhotra
R
R
Department of Biochemistry, University of Oxford, U.K.
Sim
R B
RB
D002352:Carrier Proteins; D002850:Chromatography, Gel; D003166:Complement Activating Enzymes; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D018960:Hyaluronan Receptors; D008214:Lymphocytes / Q000032:analysis*; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D008970:Molecular Weight; D009000:Monocytes / Q000032:analysis*; D011951:Receptors, Complement / Q000302:isolation & purification*
C087299:C1QBP protein, human; D002352:Carrier Proteins; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011951:Receptors, Complement; C032402:complement 1q receptor; D003166:Complement Activating Enzymes