The B Cell Receptor (BCR) Complex and the Signaling Cascades

Multiple Choice

The B cell receptor (BCR) complex and the signaling cascades to which it is linked share many similarities with the T cell receptor (TCR) complex and its linked signaling cascades. Which of the following comparisons between BCR and TCR signaling is NOT true?

A) There are ITAMs in the cytoplasmic tails of CD3 in the TCR complex and in the cytoplasmic tails of Igα and Igβ in the BCR complex.
B) The cytoplasmic tails of membrane Ig and TCR αβ antigen receptors are very short and lack intrinsic signaling functionality.
C) Early signaling events induced by antigen binding to both BCR and TCR involve both Src family and Zap-70 family protein tyrosine kinases.
D) Phospholipase C-mediated generation of IP₃ and DAG occurs downstream of both BCR and TCR signaling.
E) CD4/CD8 coreceptors in T cells and the CR2 coreceptor in B cells both enhance responses to antigen by a PI3 kinase-dependent mechanism.