A 4-Year-Old Boy Suffers from an Immunodeficiency Disease Characterized by Impaired

Multiple Choice

A 4-year-old boy suffers from an immunodeficiency disease characterized by impaired T cell activation.The disease is caused by genetic deficiency of a membrane protein whose cytoplasmic tail is involved in intracellular signaling in response to T cell receptor (TCR) recognition of antigen.Which one of the following proteins does NOT fit this description?

A) TCR $\alpha$
B) CD3 $\gamma$
C) ( $\zeta$ )
D) CD4
E) CD3?