Signal transduction - a general introduction

Alberts et al, selections from Chapters 3, 4, 11, 13, 15
(as with the membrane lecture, I will emphasize the text book)

Numbers with "#" sign refer to topis covered in more detail:
Membranes have channels
#1 For instance there are the Na+ channels of the action potential
TRANSPARENCY Fig. 11-22, p. 529
(bioelectric potentials will be covered early this semester)
Channels are gated with #1 voltage, #2 extra- & #3 intra- cellular ligands, and #4 mechanical force
TRANSPARENCY Fig. 11-18 p. 525
Such channels can be studied physiologically as individual molecules
by the patch clamp technique
TRANSPARENCY Fig. 4-55, p. 182 (see also Dwyer)
The 1991 Nobel prize was awarded jointly to: ERWIN NEHER and BERT SAKMANN for their discoveries concerning the function of single ion channels in cells (i.e. developing the patch clamp in 1976)

Extracellular ligand-gated channels are one type of receptor
TRANSPARENCY Fig.15-14 p. 732 is an outline of membrane receptor types
#2 (referring to above numbering) channel
#5 (adding to above numbers) G-protein-linked
#6 (adding to above numbers) enzyme linked

#7 In addition to cell-surface receptors, there are intracellular receptors
(the latter being the steroid hormone superfamily) [later]
TRANSPARENCY Fig. 15-2, p. 722

The ligand can diffuse or it can be membrane-bound
(the latter mechanism being used in situations like "sevenless" [later])
TRANSPARENCY Fig. 15-1 p. 722

#1 action potentials are used for rapid signalling in nerve axons and muscle cells TRANSPARENCY Fig. 11-20, p. 528
#2 the nicotinic acetylcholine receptor is an example of a channel gated by an extracellular ligand TRANSPARENCY Fig. 11-32, p. 538
#3 the rod photoreceptor cell uses an intracellular ligand (cGMP) TRANSPARENCY Fig. 15-40, p. 754
#4 the hair cell used in hearing and balance is a very specialized cell with mechanically gated channels TRANSPARENCY Fig. p. 37
#5 the G protein linked receptor typically has 7 transmembrane spans TRANSPARENCY Fig. 15-17 p. 735
and is linked to the "heterotrimeric G protein" TRANSPARENCY Fig. 15-33 p. 749 (relates to membrane lecture) with a cascade of intracellular signalling
and intracellular signalling molecules like cAMP TRANSPARENCY Fig. 15-20, p. 737
(note there are also small G proteins)
#6 receptor tyrosine kinases are examples of enzyme receptors TRANSPARENCY Fig. 15-47, p. 760. phosphorylation VERY important
These cascades are long and usually wind up at the transcriptional level
Signals include things like insulin TRANSPARENCY Figs. 3-54, p. 128, Fig. 3-14, p. 104 and Fig. 13-38, p. 628
VERY IMPORTANT: protein domains and shuffling of genes for domains
#7 steroid hormones, thyroxine, retinoic acid cross in to the cell
TRANSPARENCY Fig. 15-11, p. 729
to activate a receptor involved in gene transcription TRANSPARENCY Fig. 15-12, p. 729


T. Dwyer, A patch clamp primer, (Review Tutorial) J. Electrophysiol tech. 12, 15-29, 1985

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