Cell Signaling | Mind Map

Generic Signalling Pathway

Extracelluar Signal

Signal : ligand, molecule that binds to specific site on another molecule

Eg : Hormones, Neurotransmitter, Growth Factor, Cytokines, Antigens

Membrane Signaling events

Concept of lock and Key, allow molecule of particular shape to trigger change in chemical activity

Receptor : G-protein coupled receptor, receptor tyrosine kinase, receptor guanylate cyclase, adenylate cyclase, phospholipase

G-protein

Second Messenger

Eg : Cyclic AMP, Calcium, inositol triphosphate, nitric oxide, cyclic GMP, diacyglycerol

Intracellular Signaling

Eg ; Nitric oxide synthase, Guanylate cyclase, Calmodulin, Phosphodiesterase, CRE, CREB, Protein kinase, Protein Phosphatase

Cellular Response

Altered metabolism, altered gene expression or Altered cell shape or motility

Type of Receptor

Intracellular receptor

Fast

alter proteins function

Nitric Oxide - directly activates enzymes

Slow

alters gene expression

superfamily : Steroid Hormones, Thyroid Hormones, retinoids, Vitamin D

Cell surface receptor

Ion Channel Linked

channel protein in plasma membrane that can open and close in response to signal from ligand

important in functioning nervous system

G-protein linked

Sub Topic

Enzyme Linked

growth factor

response to extracellular signal proteins that promote growth, proliferation, differentiation, or survival of cells in animal tissues

six classes

Receptor tyrosine kinases

Sub Topic

Tyrosine-kinase-associated receptors

associate with intracellular proteins that have tyrosine kinase activity

Receptorlike tyrosine phosphatases

remove phosphate groups from tyrosines of specific intracellular signaling proteins

Receptor serine kinases phosphorylate

Receptor guanylyl cyclases

catalyze production of cyclic GMP in cytosol

Histidine-kinase-associated receptors

activate 'two-component' signaling pathway, transfer phosphate to 2nd intracellualr signaling protein

2nd Messenger & Intracellular Signaling Pathway

second messenger function is to amplify the strength of the signal

Cyclic AMP

modified ATP >stimulate G protein receptor > activate G protein > activate enzyme in membrane plasma

enzyme convert ATP into cyclic AMP > activate protein kinase

protein kinase phosphorylate other protein

another enzyme can inactivate cAMP

example:

toxin release by bacteria keep G protein active and stimulate cell lining intestine secrete large amount of water and salt

physiological effect:

enzyme activation

nerve stimulation

hormone secretion

muscle relaxation

nitric oxide (NO)

soluble and highly reactive gas produced by natural chemical and physical reaction

small and diffusible through membrane plasma

function:

biological signal

improve immune system

major factor control penile erection

play role in development, neuron to neuron signaling and contribute to formation of memories.

can inhibit oxygen consumption by mitochondria (firefly flash)

how Nitric acid and cyclic GMP related?

Nitric acid synthetase (NOS) synthesize NO from L-arginine to form L-citrulline and nitric oxide

NO diffuse out of blood vessel and enter muscle cell

NO bind with nitric acid receptor and convert GTP to cyclic GMP

cyclic GMP bind to protein kinase G

sperm nucleic acid synthesis

muscle relaxation

cell division

Type of Cell Signalling

Endocrine

Extrinsic

Endocrine

Neuronal

Neuroendocrine

Intrinsic

Paracrine

Juxtacrine

Signaling involves contact between ligand-receptor binding of two cells.

Paracrine

Signals secrete by one cell and diffuse over short ranges to bind with receptor of neighboring cells.

Autocrine

Signals secretes by a cell and bind to receptor of the same cell.

Contact dependent

Adherent junction

Holds epithelial cells together by connecting integral membrane protein to other membrane cell.

Eg: Epithelial tissue

Tight junction

Firmly bond adjacent cells together to prevent leaks within epithelial sheets.

Eg: Cells of gastrointestinal and bladder.

Gap junction

Connecting cells by providing tiny space between plasma membranes of two cells.

Eg: Heart and smooth muscle of gut.

Desmosome

Anchoring two closely adjacent non-touching cells. Mostly in considerable stretching tissue.

Eg: Cardiac muscle.

Hemidesmosome

Connect cells to extracellular material.

Exocrine

Merocrine

Cells secreting substances by exocytosis.

Eg: Sweat glands, Saliva glands

Holocrine

Entire cells disintegrate to secrete substances.

Eg: Mammary gland

Apocrine

A portion of plasma membrane containing secretion, bud off the cells.

Eg: Sebaceous glands, meibomian glands of eyelids

communication network between cell