Signal Transduction pt 1 Flashcards
What is bio-signaling?
how cells talk to each other
Cells respond to what stimuli?
-hormones
-neurotransmitters
-cytokines
-light
-odor
What are some examples of intercellular communication?
-autocrine: signal released by cell, feeds back into same cell
-paracrine: cell releases signal, affects activity of local cells
-endocrine: cell releases signal into bloodstream to some distant target cell to effect activity
What is a receptor? general
-cellular proteins that recognize and bind signaling molecules, and initiate their biological actions
-extremely high affinity and specificity (bond bind other closely related molecules)
-can be located on the cell surface, or at some intracellular site, depending on the type of signal
-transmit signal
What will determine if a receptor is on the cell-surface of intracellular?
whether it is hydrophilic or hydrophobic or solubility (low solubility - intracellular
+ vice versa)
Explain the two classes of receptors.
Intracellular: fat soluble, hydrophobic signals/hormones
-ex: steroids and thyroxine
Cell-surface: water soluble, hydrophilic signals/hormones
-ex: catecholamines, most peptide hormones, insulin, cytokines
What are the different receptor types? Examples
Surface:
-G-protein coupled receptors, receptor tyrosine kinases, receptor guanylate Cyclades, gated ion channels, adhesion
Intracellular:
-Nuclear receptors (steroids)
What are different functions of proteins?
7 things
catalytic- enzymes
structural- collagen, elastin
movement- myosin, actin
defense- clotting factors, antibodies
cell signaling- hormones, growth factors, transcription factors
transport- through membranes and blood
storage- uncommon
What proteins bind things?
enzymes- substrates, coenzymes
receptors- hormones, neurotransmitters
albumin- fatty acids
transcription factors- DNA sequences
Antibodies- antigens
Transporters- solutes
Hemoglobin, myoglobin- oxygen
What is a ligand?
What does a ligand bind to?
What does an enzyme do?
-A molecule bound reversibly by a protein
-the binding site
-bind and chemically transform substances (act on substrates rather than ligands, binding site is called a catalytic site or active site)
What is a agonist?
What is an antagonist?
What is an inverse agonist?
-a compound that binds to an activates a receptor, mimics the natural ligand
-a compound that blocks binding of an agonist, blocks the action of the natural ligand
-a compound that decreases
intrinsic activity of a receptor
What is the Kd value?
-Kd expresses the affinity of a protein for a ligand
-lower Kd=higher affinity
-equivalent to the molar concentration of ligand at which half of the binding sites are occupied
How does Benadryl work?
Benadryl is an inverse agonist at the H1 histamine receptor.
What factors affect Kd?
-temperature, pH, ionic strength
