Identification of murine complement receptor type 2.

Abstract

A rabbit antiserum reactive with the human complement component C3d/Epsteln-Barr virus receptor (complement receptor type 2, CR2) immunoprecipitates a Mr 155,000 murine B-cell surface antigen. The apparent molecular weight and cellular distribution of this murine antigen are similar to those of human CR2. Cells expressing the murine protein bind sheep erythrocytes coated with antibody and murine C1-C3d but do not bind Epstein-Barr virus at all. The monospecific antiserum to human CR2 together with goat F(ab')2 anti-rabbit IgG blocks attachment of the C3d-coated erythrocytes to receptor-bearing murine B lymphocytes. To further characterize murine CR2, a Agtll library from the murine late pre-B-cell line 70Z/3 was screened with human CR2 cDNA. A partial cDNA clone of 3.5 kilobases with 79% amino acid sequence identity to human CR2 in the unique intracytoplasmic region and 63% identity to the sixth human CR2 repeat was obtained. Blot hybridization with the murine cDNA clone identified an RNA species of -4.7 kilobases, similar in size to human CR2 mRNA, from a murine B-cell line but not from a murine T-cell line.

The crystal structure of human CD21: Implications for Epstein–Barr virus and C3d binding

“…Beyond the finding that SCR1 and SCR2 are required for attachment (13,15), little is known about the interaction of CD21 with EBV. Murine CD21 (mCD21) does not bind EBV (29), despite an overall sequence identity of 65% with hCD21 (47). Unlike hCD21, however, mCD21 contains an N-linked glycosylation site within its SCR1-SCR2 linker sequence (66-NKSI versus 66-NKYS).…”

“…CD21 mut (hCD21 with 66-NKTI replacing 66-NKYS) was synthesized (26), sequenced, and then cloned into the expression vector H3M (27). L cells transfected with either CD21 or CD21 mut together with the vector pSV2-neo (28) or with vector alone (neo) were selected with Geneticin (800 g͞ml) (GIBCO), stained with rabbit anti-CD21 (29), and sorted twice (EPICS 750 flow cytometer, Coulter) to obtain pure populations. The transfectants were stained with three anti-CD21 mAbs OKB7 (Ortho Diagnostics), HB5 (American Type Culture Collection), and B2 (Coulter) compared with relevant isotype-matched controls (23, 24), and glycosylation was documented by immunoblot (not shown).…”

“…The ability of L cells bearing CD21 or CD21 mut to bind C3d was concurrently evaluated. Sheep erythrocytes (E) coated with 7S antibody and human C3d (EAC1-C3d) were prepared (29,30). Cells were incubated with C3d-coated E for 20 min at 37°C.…”

Expression of complement receptors 1 (CR1/CD35) and 2 (CR2/CD21), and co-signaling molecule CD19 in cattle

“…CR2 (CD21), in both mice and humans, is the receptor for complement products iC3b, C3dg and C3d (Eden et al, 1973;Ross et al, 1973;Sarrias et al, 2001). There are two isoforms of CR2 in humans differing by one 58 amino acid domain; only the shorter isoform of CR2 is expressed in mice (Fingeroth et al, 1989;Ling et al, 1998;Liu et al, 1997). C3dg is the bound remnant of C3b, resulting from its cleavage and inactivation, and can be further reduced to C3d by trypsin.…”

“…In humans, CR2 also binds to the low--afBinity Fc ε receptor II (CD23) (Aubry et al, 1992;Hibbert et al, 2005) and to IFN--α , and acts as the obligate receptor for the Epstein Barr virus (EBV) (Fingeroth et al, 1984). In both mice and humans, CR2 is expressed on B lymphocytes (Fingeroth et al, 1989;Jacobson & Weis, 2008;Weis et al, 1984) and follicular dendritic cells (Reynes et al, 1985;Liu et al, 1997;Ling et al, 1998); CR2 is also expressed on human epithelial cells (Birkenbach et al, 1992). In mice, CR2 has also been detected on mucosal and peritoneal mast cells (Andrásfalvy et al, 2002;Gommerman et al, 2000).…”