BSCI330 - Unit 4: Lecture 31 - 38

Endocrine signaling

Endocrine signaling

A form of cell signaling where a signal is sent from one cell to another through the bloodstream, facilitating long-range transport.

Paracrine signaling

A type of cell signaling where a signal is sent from one cell to a nearby cell through a shared extracellular environment, enabling short-range transport within a "neighborhood."

Autocrine signaling

Cell signaling mechanism where a cell sends a signal to its own receptors.

Contact-mediated signaling

Cell signaling that occurs through direct membrane contact, where a signal from one cell binds to a receptor on another cell.

Rhodopsin

The first G protein-coupled receptor (GPCR) to be structurally characterized.

G protein-coupled receptors (GPCRs)

Important receptors in mammalian tissues, including alpha or beta adrenergic receptor, muscarinic ACh receptor, dopamine receptor, histamine receptor, and others.

GTP

Acts as a "timer" in G protein signaling, facilitating the activation of effector proteins.

FRET technique

Demonstrates the separation of G alpha from G beta gamma in cell signaling pathways through changes in fluorescence energy transfer.

Exchange factor

A protein that exchanges GDP for GTP in G protein signaling.

Inositol 1,4,5-triphosphate

When cleaved from phosphatidylinositol, it binds to receptors on the sarcoplasmic reticulum, increasing Ca2+ concentration.

Adenylyl cyclase

Receives signals for inhibition or excitation from inhibitory or stimulatory receptors, respectively.

2AR (2 adrenergic receptor)

Undergoes a 14 Angstrom outward movement at the cytoplasmic end of transmembrane 6 (TM6) to mediate activation of Gs.

Rhodopsin

Contains the light-absorbing pigment retinal and undergoes photo-isomerization from cis to trans conformation.

Rhodopsin kinase

Phosphorylates rhodopsin to attenuate its function as an adaptation to bright light.

Ampr gene (ampicillin resistance)

A gene conferring resistance to the antibiotic ampicillin.

cDNA library

A collection of cloned DNA sequences that are complementary to the mRNA extracted from an organism or tissue.

Trypsin, Chymotrypsin, Caspase

Enzymes with specific cleavage sites - Trypsin cuts after Arg (R) or Lys (K), Chymotrypsin cuts after Tyr (Y), Trp (W), or Phe (F), Caspase cleaves a cysteine after an aspartic acid residue.

Neuron morphology

Axon is on the apical side, dendrites on the basolateral side, showing polar morphology.

Na+/K+ pump

Establishes ion gradient across the membrane.

Nernst equation

Calculates reversal potentials for ions like Na+ and K+ based on their concentrations inside and outside the cell.

Action potential

Time course in a neuron shaped by currents, with K+ current delayed to allow for fast spike generated by Na+ current.

Voltage-gated Na+ channel

Functional cycle involving closed, open, and inactivated states, with a threshold around -55 to -40 mV.

Goldman equation

Relates membrane potential to ion concentrations, showing the membrane potential under standard ionic conditions for K+ and Na+.

Patch-clamp

Technique measuring current from a small area of the membrane with high spatial resolution, different from standard glass electrode measurements.

Voltage-gated K+ channel

Tetrameric structure with specific domains for sensing membrane potential, pore formation, and selectivity for K+ ions.

Capacitance

Ability to store electric charge, inversely proportional to the distance between the plates of a capacitor.

Myelination

Reduces capacitance, increasing the velocity of propagation of action potentials.

Node of Ranvier

Location of Na+ channels in myelinated axons, aiding in the rapid conduction of action potentials.

Synapse

Junction between neurons, with pre-synaptic and post-synaptic terminals, synaptic cleft, secretory vesicles, and receptors for neurotransmitters.

Neurotransmitters

Excitatory (glutamate, acetylcholine) and inhibitory (GABA, glycine) neurotransmitters and their receptors.

EPSP

Excitatory Post-Synaptic Potential - increased membrane potential

IPSP

Inhibitory Post-Synaptic Potential - decreased membrane potential

Synaptic vesicle functional cycle

The process involving vesicle import, fusion triggered by synaptotagmin and voltage-gated Ca2+ channels, neurotransmitter release, vesicle recycling via endocytosis, and vesicle docking at the plasma membrane.

Clathrin

Protein responsible for coating the membrane and forming a cage around vesicles in vesicular cycling.

Dynamin

Protein responsible for separating vesicles from the membrane (fission/scission) in vesicular cycling.

Macrophages and neutrophils

Phagocytes participating in innate immunity by engulfing and destroying invaders.

Dendritic cells

Cells detecting invaders, secreting inflammatory cytokines, and presenting antigens in innate immunity.

Natural killer cells

Cells that secrete perforins and granzymes to kill infected cells in innate immunity.

Mast cells

Cells that secrete histamine and heparin in innate immunity.

Opsonins

Molecules that decorate pathogens for easier recognition by T cells.

Defensins

Molecules that degrade the cell wall of pathogens.

Complement

Proteolytic cascade resulting in a large membrane pore in innate immunity.

PAMPs

Pathogen-Associated Molecular Patterns - conserved motifs associated with pathogen infection.

TLR 3, 4, 5 recognition

TLR3 recognizes double-stranded RNA, TLR4 recognizes LPS, and TLR5 recognizes flagellin.

NF-kB

Transcription activator responsible for multiple stress responses.

Adaptive immune system vs

Differences in recognizing molecular patterns, activity timing, and antibody generation.

Antibody structure (IgG)

Includes light and heavy chains, disulfide bridges, and hypervariable loops.

Antigen presentation

Process where APCs present peptide fragments on MHC molecules to activate T cells.

Professional APCs

Macrophages, dendritic cells, and B cells involved in antigen presentation.

B-cell receptor (BCR)

A receptor found on the surface of B cells that recognizes antigens.

Antigen-presenting cell (APC)

A cell that processes and presents antigens to T cells.

CD4 helper T cell

A type of T cell that helps activate B cells by interacting with them.

MHCII

Major Histocompatibility Complex II, a protein complex that presents antigens to CD4 T cells.

Plasma cell

A differentiated B cell that produces antibodies.

CD40-CD40L co-receptors

Molecules involved in the interaction between B cells and T helper cells.

Activation-induced deaminase (AID)

An enzyme involved in antibody diversification.

Class-switch recombination

A process where B cells change the class of antibodies they produce.

MHC I

Major Histocompatibility Complex I, a protein complex that presents antigens to CD8 T cells.

MHC II

Major Histocompatibility Complex II, a protein complex that presents antigens to CD4 T cells.

Proteasomes

Protein complexes that degrade proteins into peptides.

Lysosomes

Cellular organelles that degrade extracellular material.

VDJ recombination

The process of combining gene segments to generate diverse antibodies or T cell receptors.

RAG1 and RAG2

Enzymes involved in VDJ recombination.

Memory B-cells

B cells that provide long-lasting immunity by circulating after an infection.