LEHNINGER PRINCIPLES OF BIOCHEMISTRY

Sixth Edition

David L. Nelson and Michael M. Cox

© 2013 W. H. Freeman and Company

CHAPTER 12Biosignaling

Five features of signal transducing systems

Six general types of signal transducers

The β-adrenergic receptor is a G protein-coupled receptor

Adenylyl cyclase produces cyclic AMP (cAMP) from ATPcAMP is a potent second messenger in epinephrine signaling

The GTPase switch

Regulation of epinephrine

signaling

Activation of cAMP-dependent protein kinase (PKA)

Epinephrine cascade

Desensitization of the β-adrenergic receptor in the

continued presence of epinephrine

Hormone-activated phospholipase C

(PKC) and inositol 1,4,5-triphosphate

(IP3)

Calmodulin often mediates the

effects of calcium

Insulin signalingThe insulin receptor is a

tyrosine kinase

The electrogenic Na+K+ ATPase

produces a transmembrane

electrical potential of about -60 mV

(negative inside the cell)

Free energy change for charged molecule

G = RT ln ( Cin / Cout) + FVm

Z=valence, F=96,500 J/V*mol, Vm=TM electrical potential (volts)

Role of voltage-gated and ligand-gated ion channels in neural

transmission

The acetylcholine receptor ion channel

Steroid hormones