cell signallng

what do cells use to talk

ligands

what do cells use to listen

receptors

what’s the term for signaling between two different cells

intercellular

what’s the term for signaling within one cell

intracellular

why is cell communication important

cell development, tissue homeostasis, immune system

what are 4 general types of cell-cell communication

endocrine, paracrine, juxtacrine, autocrine

what’s another term for juxtacrine signaling

contact dependent

difference between juxtacrine and paracrine

juxtacrine needs contact

why do cells receive signals

to grow, differentiate, or perform immediate functions

are intracellular enzymes that change gene expression or signalling molecules between cells more conserved between plants and animals

intracellular enzymes

what main pathways did we focus on

gpcrs and rtks

what other pathways did we talk about

jak-stat, wnt, notch

what type of messenger are signalling molecules

primary

characteristics of receptor activation

highly specific, noncovalent, temporary, receptor undergoes conformational change

are ligands super specific for their receptors

no the same ligand can elicit different responses in different cell types

what kind of receptor is the androgen receptor

nuclear

what kind of signalling molecules reach nuclear receptors

hydrophobic ones

what are some examples of signaling molecules that bind nuclear receptors

steroids, retinoic acid, and thyroid hormone

what are domains of nuclear receptors

ligand-binding, DNA-binding, activation domain

what are 4 steps of nuclear receptor signaling

hormone frees trapped transcription factors, receptor dimerizes in nucleus, binds a response element, and activation domain triggers transcription

other name for ligand gated ion channel

ionotropic receptors

where are ionotropic receptors common and why

neurons and muscles; action potentials and rapid changes

what ligands are common in ionotropic signaling

acetylcholine and glutamate

what are four common components in signal transduction

protein kinases (and phosphatases), small diffusible molecules (second messengers), g-proteins (on/off switches), and adapter proteins

what do kinases do

use atp to phosphorylate proteins

what do phosphatases do

reverse phosphorylation (remove phosphates)

how many kinases do humans have

600

how many phosphatases do humans have

100

kinases in animals/plants

serine/threonine

kinases in animals/fungi

tyrosine

kinases in plants, protists, and prokaryotes

histidine

what are second messengers

small, diffusible, non-protein molecules that spread signal throughout the cell

what do second messengers do

bind effector proteins

where do second messengers come from

can be released or made

what are some common second messengers

cyclic amp/gmp, DAG, IP3, Ca

where do cyclic amp and gmp come from

synthesized from ntp by cyclase enzymes

what does phosphatidylsitol split into

diacyl glycerol (DAG) which diffuses in membrane and inositol triphosphate (IP3) which diffuses in cytosol

why does calcium ions make good second messenger

calcium concentrations are low in the cytosol

what do g proteins do

bind and activate effectors (enzymes, channels)

when is g protein '“on”

when bound to GTP

when is g protein “off”

bound to GDP

what are adapter proteins similar to

maps of ECM

what do adapter proteins in cell

cluster proteins in the cell

why is signal transduction important

many drugs are inhibitors or activators of these pathways

what connects most transduction proteins

cancer