CELL SIGNALING

CELLULAR PROCESS PRESENTATION

BY:-MOIN KHAN HUSSAIN UID:-14BBT1129

Cell Signaling

A. Types of Cell Signaling

B. Intracellular Receptor Signaling: Steroid Hormones

C. Cell Surface Receptors: Types

D. Cell Surface Receptors: G-protein

linked receptors

A. Types of Cell

Signaling

• Direct cell-cell signaling vs.

signaling via secretion

A. Types of Cell

Signaling

• Cell surface receptors vs.

Intracellular receptors

A. Types of Cell Signaling• Three forms of signaling by secreted

molecules

– Paracrine

– Synaptic

– Endocrine

Endocrine further divide into two part:-

A. Types of Cell

Signaling

• Gap junctions

A. Types of Cell

Signaling

• The same signal can produce different

effects in different cells

A. Types of Cell

Signaling

• Types of Signals based on

Where they Bind

– To an intracellular receptor:

e.g. Steroid hormones

– To a cell-surface receptor: G-protein linked,

enzyme-linked, or ion channel-linked


• Overview of Steroid Hormone Action:– Steroid hormone (small, hydrophobic) is

secreted by glandular cells and released into bloodstream (usually transported via shuttle proteins)

– The hormone enters the cytoplasm of cells

– In the cytoplasm of target cells, the hormone binds to steroid hormone receptor protein


• Overview of Steroid . . . (cont.):– The steroid-receptor conplex is

translocated into the nucleus, where it activates the transcription of the primary response genes

– Transcription of the primary response genes, followed by translation, results in the production of primary response proteins


• Overview of Steroid . . . (cont.):

– The primary response proteins usually inhibit further transcription of their own genes, and they may activate transcription of secondary response genes.

C. Cell Surface Receptors:

Types

• Three known classes of cell surface

receptors

– Ion channel-linked, G-protein-linked, Enzyme-

linked

– An activated cell-surface receptor triggers a

phosphorylation cascade

D. Cell Surface Receptors: G-protein linked receptors

• Largest family of cell surface receptors

– Different ones respond to a wide variety of mediators including

different hormones, neurotransmitters, local mediators

– Examples: Receptors to epinephrine, acetylcholine, serotonin

B. G-linked Receptors

• What do G-protein receptors do?

– G-protein receptors activate trimeric G-protein

– Activated G-protein alters the cellular

concentration of a “second messenger”: usually

cyclic AMP or Ca2+

– The second messenger activates a protein

kinase enzyme

– The protein kinase phosphorylates another

enzyme and alters its activity


• Trimeric G-proteins disassemble when

activated

– Three chains: a, b, and g

a chain binds and hydrolyzes GTP

b & g chains form a tight complex bg that

anchors G-protein to the plasma membrane


• Action of epinephrine on glycogen

metabolism

– Epinephrine (adrenaline) is released from the

adrenal gland in times of stress. It has two

overall actions on glycogen metabolism: it

inhibits glycogen synthesis, and it promotes

glycogen breakdown

– This is mediated by a protein phosphorylation

cascade

SUMMARY

1. Types of Cell Signaling

2.Intracellular Receptor Signaling: Steroid Hormones

3.Cell Surface Receptors: Types

4.Cell Surface Receptors: G-protein

linked receptors

THANK YOU!!!MOIN KHAN

HUSSAINUID:-14BBT1129

Healthcare

CELL SIGNALING