The interaction of CD28 with its ligands, B7-1 (CD80) and B7-2 (CD86) on antigen-presenting cells enhances a number of TCR-mediated responses like production of interleukins. CD28 mediated costimulation is dependent upon phosphorylation of tyrosine residue 191 of the CD28 cytoplasmic tail, present in a 'YMNM' motif. p56Lck and p59Fyn phosphorylate CD28 and the phosphorylated residue allows the recruitment of PI3K, growth factor receptor-bound protein 2 (GRB2) and Grb2-related adaptor downstream of SHC (GADS) via their src-homology region 2 (SH2) domains.
Truitt, KE, Imboden, JB, Cinek, T, Arellano, JL, Shi, J, Sadra, A
August, A, Selvakumar, A, Dupont, B, King, PD, Liu, X, Sadra, A, Han, A, Teng, JM
protein tyrosine kinase activity of Src family tyrosine kinases (SFKs) [cytosol]
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