GLP-1 and Cell-Signaling

GLP-1

ligand that increases secretion of insulin from pancreas (short-lived)

hormone

cell signaling molecule secreted into bloodstream and carried to distant target cell (used in endocrine signaling)

endocrine

hormones released into bloodstream to travel to distant target cells

autocrine

self-signaling

juxtacrine

signals act on directly adjacent cells through physical contact

paracrine

signals diffuse through local tissue and act on nearby cells

ligand-binding and effector specific

receptor proteins are _____

effectors

proteins upstream/downstream that can be stimulatory or inhibitory

GLP-1R

receptor, G protein-coupled receptor (GPCR), extracellular domain determines ligan specificity, cytoplasmic domain determines G protein specificity

G-protein (guanine nucleotide-binding proteins)

on-off switch/molecular timer that causes GPT to turn into GDP

heterotrimeric G proteins

3 subunits: alpha (binds to GTP/GDP), beta and gamma heterodimer

effector enzyme of GPCR signaling

Gas, Gai

adenylyl cyclase

makes cyclic amp (cAMP)

turns on cAMP-activated protein kinase that causes PKA to dissociate so it can phosphorylate specific protein target in cell

cAMP function