Identification of an alternatively spliced form of the murine homologue of B7.
B7 on antigen presenting cells is a costimulatory ligand necessary for full activation of T cell. Receptors for B7 have been known as CD28 or CTLA4. We here show that in addition to B7 mRNA, an alternatively spliced mRNA (designated as MB7-2 mRNA), that immunoglobulin (Ig)C-like domain coded by exon 3 has been spliced out, is found in activated murine splenic B cells by reverse transcriptase-polymerase chain reaction analysis. Chinese hamster ovary (CHO) cells transfected with MB7-2 bound CTLA4Ig less well than those expressing B7, but bound CD28Ig to a similar extent, indicating that IgV-like domain contains the complete binding site for CD28. In addition, IgC-like domain may participate in an increase in the affinity for CTLA4. Thus, MB7-2 represents a new form of the murine B7 with different receptor binding properties.
Inobe
M
M
Section of Immunopathogenesis, Hokkaido University, Sapporo, Japan.
Linsley
P S
PS
Ledbetter
J A
JA
Nagai
Y
Y
Tamakoshi
M
M
Uede
T
T
D017398:Alternative Splicing; D000818:Animals; D000911:Antibodies, Monoclonal; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D018122:B7-1 Antigen / Q000096:biosynthesis*; D001483:Base Sequence; D016466:CHO Cells; D002478:Cells, Cultured; D003001:Cloning, Molecular; D006224:Cricetinae; D017931:DNA Primers; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis*; D012194:RNA-Directed DNA Polymerase; D013154:Spleen / Q000276:immunology; D014162:Transfection
D000911:Antibodies, Monoclonal; D018122:B7-1 Antigen; D017931:DNA Primers; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D012194:RNA-Directed DNA Polymerase