Biochemistry Chapter 14 Extended

Transduction

the conversion of information of the presence or concentration of a signal molecule into other forms

Primary messenger

hormone, neurotransmitter, or other molecule that carries information to a cell or tissue by binding to a receptor, usually on the cell surface

Receptors

biological macromolecule, usually a cell-surface protein, that binds a molecule such as a hormone and initiates signaling cascades; spans the membrane

Second messngers

intracellular signaling molecule (such as a calcium ion or cyclic AMP) whose concentration changes in response to the arrival of a primary messenger

Epinephrine

hormone released under conditions of stress that increases heart rate, blood circulation, and carbohydrate metabolism

Andreneric receptors

cell-surface receptor that signals in response to the bonding of adrenaline

7TM receptors/ G-protein coupled receptors (GPCRs)

member of a class of cell-surface receptors with 7 membrane spanning a helices that signal through G proteins

G protein

a signaling protein that depends on binding guanine (G)-containing nucleotides

Agonists

molecule or ligand that binds to and activates a receptor

Adenylate cyclase

enzyme that converts ATP into cAMP

Calmodulin

protein present in many cells that binds calcium ions, changes conformation, and binds action a-helical structures, often to activate enzymes

EF hand

a Ca2+ binding motif that consists of a helix, a loop, and a second helix

Antagonists

compounds that bind to the receptor, but doesn’t activate it, blocking the effects of the activating ligands (agonists)

Insulin

hormone secreted by the pancreas that promotes the absorption of glucose from the bloodstream

Activation loop

structure found in protein kinases that changes conformation, often in response to the phosphorylation of specific tyrosine or serine/threonine residues

Pleckstrin homology domain

protein domain that binds phosphatidylinositol lipids

Oncogenes

gene that initiates the development of cancer

Mutated Ras genes are ____

oncogenes

Proto-oncogenes

normal genes that can be converted to an oncogene by mutation

Unmutated Ras genes are ____

proto-oncogenes

Tumor-suppressor genes

can suppress the development of cancer even if present in only a single copy