Lecture 21 - Cell Signalling and Signal Transduction Flashcards
def: produced far from the target tissues, which they reach via the circulatory system
endocrine
def: diffusible and act “locally” or over a short range. their distribution is usually limited by their inherent instability
paracrine
def: act on the same cell that produces them
autocrine
def: many of these molecules act as neurotransmitters and hormones, such as epinephrine
amino acids and their derivatives
def: cholesterol derivatives, which regulate sexual differentiation, pregnancy, carbohydrate metabolism, and ion excretion
steroids
def: fatty acids that regulate pain, inflammation, blood pressure, and blood clotting. NSAIDs block their synthesis
eicosanoids
def: a wide variety of secreted proteins act as ligands, regulating processes such as cell division, differentiation, cell death/survival and the metabolism
polypeptides and proteins
what are the 3 main classes of cell surface receptors?
- G-protein coupled receptors
- enzyme-linked receptors (RTK)
- ion channel linked receptors
what is the requirement for cells to respond to a particular ligand?
they must express the receptor that specifically recognizes and binds the messenger
receptors have ________ _______ that fits the ligand very closely
binding site
ligands bind to receptors in a highly specific way, through _____ _______ ___________-
non-covalent interactions
def: relationship between the [ligand] in solution and the number of receptors occupied
receptor affinity
def: the [free ligand] needed to produce a state in which half the receptors are occupied
dissociation constant Kd
receptors with high affinity for their ligand, have ____ Kd, and vice versa
low
def: drugs that activate the receptor they are bound to
agonists
def: drugs that bind receptors without activating it, thus preventing the naturally occurring messenger from activating the receptor
antagonists
what is isoproterenol used to treat and is it an antagonist or agonist?
- treat asthma
- agonist of the epinephrine G-protein coupled receptor on bronchial smooth muscle
what is alprenolol used to treat and is it an antagonist or agonist?
- anxiety attacks or cardiac arrhythmias
- antagonist that blocks the affect of epinephrine responsive receptor on cardiac muscle cells that increases heart rate contraction, therefore slowing the patient’s heart rate
what is generally the first step of a cell signalling pathway?
extracellular ligands, called “first messengers” bind to a receptor triggering a signalling cascade
what does ligand binding induce in the transmembrane receptor protein and what does it do?
induces a conformation change in the receptor protein which acts to relay the signal across the membrane
the _________ __________ _____________ of a transmembrane receptor protein can act as or activate effector molecules
active cytoplasmic domain
def: some effectors generate small molecules or ions that relay signals from one location to another in the cell
second messengers
once proteins near the “top” of the intracellular signalling pathway are activated, what happens?
a series of protein modifications occur, in a specific sequence
each protein in the cascade acts on the subsequence protein, ________ ____ __________, leading to _______ _____ ____________ of the downstream protein
altering its conformation, activation or inhibition
