Part II: Antigen Receptor Structure and Signaling Pathway Specifics
•The BCR and the TCR are multi-protein complexes composed of both variable antigen binding chains and “invariant” accessory chains.
•The variable Ag binding chains lack substantial cytoplasmic tails for signaling; the accessory chains are necessary for 1.) transport of the antigen receptor to the cell surface and 2.) initiating signaling following binding of antigen.
•Antigen binding in mature lymphocytes ultimately leads to activation of transcription factors which turn on certain genes and turn off inhibitory genes expressed in resting cells.
•Pre-T and pre-T cell receptors (chapter 7) employ same accessory molecules for signal transduction in developing T and B progenitors.