Evidence that the two C1q binding membrane proteins, gC1q-R and cC1q-R, associate to form a complex.
J Immunol
; 159(3): 1429-36, 1997 Aug 01.
Article
em En
| MEDLINE
| ID: mdl-9233640
Two types of widely coexpressed, highly acidic, cell membrane binding proteins that display preferential domain specificity for C1q have been described: a 60-kDa calreticulin homologue, designated cC1q-R, that binds to the collagen-like "stalk" and a 33-kDa glycoprotein with affinity for the globular "heads" (gC1q-R). Although the two molecules are known to be coexpressed on all cell types examined to date and often coelute during purification, there is no direct evidence showing that they associate with each other either on the membrane or when examined in a purified system. In this report we present the first evidence that 1) biotinylated cC1q-R binds to recombinant as well as native gC1q-R, as assessed by solid phase ELISA; 2) binding sites for cC1q-R are located within N-terminal residues 76 through 93 of the mature form of gC1q-R and within residues 204 through 218; 3) this interaction is inhibited by two mAbs, 60.11 and 46.23, that recognize primarily epitopes within the N terminus of gC1q-R corresponding to residues 74 through 96 and by mAb 74.5.2 that recognizes epitopes within residues 204 through 218; and 4) biotinylated cC1q-R binds to microtiter-fixed Raji and K562 cells, and this interaction is inhibited by mAb 60.11. Furthermore, coimmunoprecipitation analysis of Raji cell membranes with anti-gC1q-R mAbs showed the presence of cC1q-R in addition to gC1q-R. Taken together, the evidence suggests that cC1q-R is able to form a complex with gC1q-R and may associate with gC1q-R on the cell surface.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Glicoproteínas de Membrana
/
Receptores de Complemento
/
Complemento C1q
/
Receptores de Hialuronatos
Tipo de estudo:
Risk_factors_studies
Limite:
Humans
Idioma:
En
Revista:
J Immunol
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
Estados Unidos