membrane protein signaling Flashcards
plasma membrane receptors with an _________________________________ act through _________ of protein kinases to transduce signals about the metabolic state, including growth factors
intracellular tyrosine kinase activity; cascades
insulin receptor substrate 1 (IRS1)
becomes the point of nucleation for a complex of proteins that carry the message from the receptor to end targets
SH2 domain
binds phosphorylated Tyr residues in a protein partner
what happens during insulin regulation?
insulin receptor binds insulin and undergoes autophosphorylation on its carboxyl-terminal Tyr residues; insulin receptor phosphorylates IRS1 on its Tyr residues; SH2 domain of Grb2 binds to P-Tyr of IRS1. Sos binds Grb2, then to Ras, causing GDP release and GTP binding to Ras; Activated Ras binds and activates Raf-1; ERK moves into the nucleus, and phosphorylates nuclear transcription factors such as Elk1, activating them; phosphorylated Elk1 joins SRF to stimulate the transcription and translation of a set of genes needed for cell division
activation of ____ by phosphorylated IRS1 initiates movement of GLUT4 to the plasma membrane and activation of glycogen synthase
PI3K
ion channels gated by membrane potential or ligands are central to
signaling in all cells, including bacteria, plants, and animals
ion channels open when …
a specific ligand binds to its associated receptor or there is a change in the transmembrane electrical potential
what is the resting potential?
when the membrane is depolaried
what establishes the membrane potential?
electrogenic Na+K+ ATPase
action potential
wave of depolarization (Na+ influx) followed by repolarization (K+ efflux)
travels length of neuron from the cell body to the end of an axon; carried by voltage-gated Na+ and K+ channels of neuronal membranes; arrival at the distal end of a presynaptic neuron triggers neurotransmitter release
some hormone signals act ______________, not at the plasma membrane, forming _________ with specific receptor proteins that ________________________________
inside the cell, complexes, regulate gene expression
nuclear hormone receptor
hormone, carried to the target tissue on serum binding proteins, diffuses across plasma membrane and binds to specific protein in the nucleus; hormone binding changes conformation of receptor; receptor attracts coactivator or corepressor proteins, and with them, regulates transcription of the adjacent genes, increasing or decreasing rate of mRNA formation; altered levels of hormone-regulated gene product produce cellular response to hormone
