Cell Biology

... from active transport to vesicles

receptor proteins

Biologically active molecules (ligands) exert their physiological effect by activating or inducing 3D conformational changes in receptor proteins, which participate in signal transduction, cellular signaling, gene regulation, cellular proliferation and differentiation, or regulation of cellular metabolic processes.

Right - click to enlarge - Cartoon representation of a complex between DNA and the ZIF268 protein, containing 3 zinc finger motifs. The coordinating residues of the middle zinc finger are highlighted. Based on the x-ray structure of PDB 1A1L. Color coding: ZIF268: blue; DNA: orange; Zinc ions: green Author: Thomas Splettstoesser Download high-resolution version (1188x1114, 410 KB)

Receptor proteins are located in the cytoplasm, cell membrane, or nuclear membrane.
1. Cytoplasmic receptor proteins include those that respond to steroid hormones. Ligand activated receptors may enter the cell nucleus where they modulate gene expression.
2. Receptors within cell membranes may be peripheral or trans-membrane proteins. Many receptors for hormones and neurotransmission are trans-membrane proteins.
_a. Metabotropic receptors are coupled to G proteins, acting through various secondary pathways involving ion channels, enzymes such as adenylyl (adenylate) cyclases, and phospolipases, or PDZ domains.
_b. Ionotropic receptors are ligand-activated ion channels that permit entry of ions when the central pore is open.

active transportion channels [] image - receptor proteins [] 3D image steroid receptor - Zn finger Џ animation - receptor protein :

There are more than 1200 individual human plasma membrane receptors in more than 20 families. Examples of receptor proteins/receptors include:
a. Guanine nucleotide-binding protein-coupled receptors (GPCRs) (metabotropic).
b. serine threonine kinases (SerThr Kinase) : TGF-β; MAPK cascade; phosphoinositol kinase-related kinase (PIKK) family - mTOR (FRAP1), ATM, ATR, DNA-PK
c. receptor tyrosine kinases (RTKs) : EGFR, Tie receptors, Eph RTKs,
d. cytokine receptors
e. integrins
f. TNF receptors : FAS

Џ beautiful Flash 8 animation - Inner Life of the Cell, which shows membrane adhesion-signaling, and Interpretation: Inner Life of the Cell Џ

• A • adhesion • C • cell membranescellular adhesion moleculescellular signal transductioncentrioleschemotaxischloroplastcilia & flagellacommunicationconcentration gradientscytokine receptorscytoplasmcytoskeleton • E • energy transducersendoplasmic reticulumendosomesexosome • F • flagella & cilia • G • Golgi apparatusGPCRs • H • hormones • I • ion channels • L • lysosome • M • meiosismicrotubulesmitosismitochondrion • N • Nitric Oxideneurotransmissionneuronal interconnectionsnuclear membranenuclear pore • P • pinocytosisproteasomeprotein degradationpumps • R • receptor proteinsreceptor-mediated endocytosis • S • second messengerssignaling gradientssignal transductionspindlestructure • T • transporttwo-component systems • U • ubiquitin • V • vacuolevesicle

. 7 TM receptors & GPCRs . Toll . NPR . Integrins . LDL receptors & LRP . Notch . Patched Plexins . Roundabout . RPTPs . RTKs . Ser/Thr Kinase receptors . TNF receptors . Cytokine 1 receptors . T-cell receptors . Cytokine 2 receptors . Netrin receptors .


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