B7 family
b7 family
B7 is a type of peripheral membrane protein found on activated antigen presenting cells (APC) that, when paired with either a CD28 or CD152 (CTLA-4) surface protein on a T cell, can produce a costimulatory signal or a coinhibitory signal to enhance or decrease the activity of a MHC-TCR signal between the APC and the T cell, respectively.  Binding of the B7 of APC to CTLA-4 of T-cells causes inhibition of the activity of T-cells.  There are two major types of B7 proteins: B7-1 or CD80, and B7-2 or CD86. However, it is not known if they differ significantly from each other. CD28 and CTLA-4 each interact with both B7-1 and B7-2.