Final answer:
Calcium ions (Ca²⁺) and diacylglycerol (DAG) are second messengers in the T-cell signaling pathway that lead to the activation of NFAT through the action of PLC-γ and PKC.
Step-by-step explanation:
Calcium ions (Ca²⁺) and diacylglycerol (DAG) are second messengers in the T-cell signaling pathway that lead to the activation of NFAT (nuclear factor of activated T-cells). In the signaling pathway, the binding of a peptide hormone to a cell surface receptor triggers the activation of phospholipase C-gamma (PLC-γ) via a G-protein.
PLC-γ then catalyzes the hydrolysis of phosphatidylinositol bisphosphate into two second messengers: inositol triphosphate (IP3) and DAG. IP3 is soluble and initiates the release of Ca²⁺ ions from the endoplasmic reticulum into the cytoplasm, while DAG remains in the membrane.
Together, Ca²⁺ ions and DAG activate protein kinase C (PKC). PKC then initiates a phosphorylation cascade that results in the activation of NFAT, which translocates to the nucleus to modulate gene expression.