Pumps and Carriers

1
Pumps and Carriers

• Peter Maloney
• pmaloney_at_jhmi.edu

2
Chemiosmotic Circuits Rules of Thumb
Classification Experiments in Glucose
Transport Structure and Mechanism The Na
Circuit of Mammalian Cells
Pumps and Carriers
Peter Maloney pmaloney_at_jhmi.edu
3
A Simple Chemiosmotic Cycle
4
Superfamilies of ATP-Driven Pumps
5
Chemiosmotic Circuits Rules of Thumb
Classification Experiments in Glucose
Transport Structure and Mechanism The Na
Circuit of Mammalian Cells
Pumps and Carriers
Peter Maloney pmaloney_at_jhmi.edu
6
0.2 µ
The Nernst Equation EK -(RT/zF) ln IN /
OUT EK -120 mV (912 of 377,000 K
leave)
7
Fractional Loss in Cells of Different Radii
8
Rules of Thumb
Movement of only a few charges will generate a
membrane potential of significant size (
120 mV) Internal and external concentrations
do not change If a chemical gradient forms,
think carefully
9
Acidification of the Lysosome
10
Acidification of the Lysosome
11
Chemiosmotic Circuits Rules of Thumb
Classification Experiments in Glucose
Transport Structure and Mechanism The Na
Circuit of Mammalian Cells
Pumps and Carriers
Peter Maloney pmaloney_at_jhmi.edu
12
Classification of Transporters
http//www.biology.ucsd.edu/msaier/transport/
13
General Nomenclature Carrier
Facilitator Porter Common
Biochemical Mechanisms Uniport (GLUT1)
Facilitated Diffusion Antiport (OxlT)
Exchange or Counter-transport Symport
(LacY) Cotransport Members of the Major
Facilitator Superfamily
14
(No Transcript)
15
Chemiosmotic Circuits Rules of Thumb
Classification Experiments in Glucose
Transport Structure and Mechanism The Na
Circuit of Mammalian Cells
Pumps and Carriers
Peter Maloney pmaloney_at_jhmi.edu
16
Experiments with the Red Cell
17
The Carrier Hypothesis
18
Variants of the Carrier Model