ACTIVE TRANSPORT

(from Berg, Tymoczko & Stryer, Biochemistry, 5th Ed.)

Calcium-ATPase(Toyoshima et al., Nature 2000, 405, 647-655)

Ca2+-ATPase

P domainP domain

Ca2+ ions

Cytosol

Asp 351A domainA domain

N domain

Mechanism:

ACTIVE TRANSPORT 2

Lactose Permease(Abramson et al., Science 2003, 301, 601)

Mechanism:

Lactose/Proton Symporter

F1F

0 ATP synthase

ATP synthase web page: http://www.atpsynthase.info/

Boyer, Annu. Rev. Biochem. 1997, 66, 717; Abrahams et al. Nature 1994, 370, 621;

Dimroth et al. EMBO Reports 2006, 7, 276

F1 ATPase

ADP + Pi + n Hout

ATP + n Hin+

+

StatorAxle

mitochondrion

ultrasound

SMP F1

membrane matrix

H+

H+ H+

Fo

F1

ATPase

ADP + Pi

ATP

ATP

synthase

NADH NAD+

a

subunit

ring of

c subunits

H+

H+

Asp61

Fo subunit c

PDB 1A91

ATP

Binding-change mechanism for ATP synthesis

repeat

ADP

+ Pi

ADP + Pi

ATP

ATP

ATP

ATP tight

binding

loose binding

open

ADP

+ Pi

Direct observation of ATP-driven rotation in ATP synthaseNoji et al. Nature 1997, 386, 299; Yasuda et al., Cell 1998, 93, 1117

actin filament

F1

Rotation of relative to &

Proton motion across the membrane drives rotation of the c ring relative to the a subunit

F1 ( )

3 subunits; the subunit, which serves as a “shaft”, is at the 3-fold axis

THE PATCH CLAMP TECHNIQUENeher & Sakmann, Sci. Am. 1992, 266, 28

By pressing a patch pipette against the enzymatically cleaned surface of a cell and applying gentle suction, researcherscan place a gigaohm seal around a small patch of membrane and the ionchannels it contains. The behavior ofthe trapped channel can be measuredupon application of various stimuli fromwithin the pipette.

Receptor channels found at the neuro-muscular end plate open in responseto the transmitter acetylcholine. Whenno acetylcholine is present, effectivelyno current passes through a channel.When acetylcholine binds to the receptor, an elementary current of afew picoamperes flows. The measureddurations of the currents and theintervals between them vary becausethe interaction of acetylcholine molecules with the receptors isgoverned by probability.

Genetically engineered frogs eggs areuseful tools for studying ion channelbehavior. RNA sequences encodingsubunits of ion channels can be injected into an egg (a). The egg willthen synthesize the channel proteinsand insert them into its surfacemembrane, where they are accessiblefor patch clamp experiments (b).

A CATION-! BINDING SITE IN THE NICOTINIC RECEPTORZhong et al., Proc. Natl. Acad. Sci. USA 1998, 95, 12088-12093

H3CN O

CH3H3CO

CH3+

Replacement of Trp149of the "-subunit

PASSIVE TRANSPORT

(from Berg, Tymoczko & Stryer, Biochemistry, 5th Ed.)

A single subunit

10 Å

34 Å

12 Å

3 Å

View down the pore

Path through the channel

Selectivityfilter

Potassium channel (Doyle et al., Science 1998, 280, 69-77)

A1 = 2-adamantanamine; A2 = 1-adamantanecarboxylic acid

STOCHASTIC SENSING OF ORGANIC ANALYTES Gu et al., Nature 1999, 398, 686-690