Question

The role of the CD₅ co-receptor proteins on the surface of the T cell is to:

A. transduce signals to the interior of the T cell
B. bind to antigen associated with MHC molecules
C. bind to MHC molecules
D. bind to CD₄ or CD₈ molecules
E. facilitate antigen processing of antigens that bind to the surface of
T cells.

Answer 1

The role of CD₅ co-receptor proteins on T cells, specifically CD4 or CD8, is to bind with MHC molecules and transduce activation signals to the T cell, thus playing a pivotal role in the immune response.

Step-by-step explanation:

The role of the CD₅ co-receptor proteins on the surface of the T cell is to transduce signals to the interior of the T cell. Specifically, CD4 or CD8 molecules, which are types of CD₅ co-receptors, maintain close contact with antigen-presenting cells by binding to Major Histocompatibility Complex (MHC) molecules. While the T cell receptor (TCR) binds to processed antigen fragments presented on MHC molecules, the CD4 or CD8 co-receptors assist in this binding and signal the T cell to become activated, helping the immune response.

CD4+ T cells interact with class II MHC molecules usually found on professional antigen-presenting cells (APCs) and are instrumental in helper T cell function, while CD8+ T cells bind to class I MHC molecules found on all nucleated cells and are key to cytotoxic T cell function. The recognition of the antigen and MHC complex by the TCR, assisted by these co-receptors, leads to T cell activation which is crucial for appropriate immune system response.