Final answer:
The GCPR-AC pathway is stimulated by the activation of adenylyl cyclase, leading to the production of cAMP and activation of PKA or PKC, which then triggers a cascade of cellular responses. It is key to various physiological responses and needs proper regulation to prevent diseases.
Step-by-step explanation:
GCPR-AC Pathway Activation
The student is inquiring about the stimulation of the GCPR-AC pathway which involves the activation of adenylyl cyclase and production of second messengers, specifically cAMP. This pathway begins when an external signal molecule like a hormone binds to a G-protein coupled receptor (GPCR), which then activates a G-protein on the inner side of the plasma membrane. Upon activation, the G-protein's α subunit binds to adenylyl cyclase, stimulating the conversion of ATP to cAMP. cAMP then acts as a second messenger, activating protein kinase A (PKA), which initiates a cascade of phosphorylation events leading to various cellular responses.
Inositol triphosphate (IP3) and diacyl glycerol (DAG), involved in the PKC pathway, are also produced by the phospholipase C enzyme after being activated by a G-protein. IP3 promotes the release of calcium ions from the endoplasmic reticulum into the cytoplasm, and in concert with DAG, activates Protein Kinase C (PKC), which phosphorylates other proteins leading to cell-specific responses.
The GCPR-AC pathway is significant in many cellular processes such as energy storage, gene expression, cell division, and programmed cell death (apoptosis). Regulation and termination of the signaling is crucial to maintain proper cellular function, with dysregulation potentially leading to conditions such as diabetes, heart disease, and cancer.