Transcript Document

15.10, 589
ATP-dependent ion pumps—maintain ion gradients against
concentration gradient
-20-50% of all ATP hydrolyzed used by these pumps-even in muscle
-if you poison ATP synthesis, eventually ions will come to
equilibrium across membrane (all cells have a certain rate of
leakage of ions across membrane)-constantly bailing the boat
-many think that ion pumps are responsible for metabolic rate
15-2, 590
15.11, 592
Calcium ATPase, sometimes called SERCA
-what moves calcium in your muscle-allows muscle to contract
and relax
~1000 amino acids, and over 200 have been studied by sitedirected mutagenesis
MacLennan, DH
and Toyofuku, T.
1996. Regulatory
interactions
between calcium
atpases and
phospholamban.
Organellar Ion
Channels and
Transporters.
Rockefeller Univ.
Press.
-isoforms for slow muscle, fast, smooth, nonmuscle
(plasma membrane)
-switch muscle type switch SERCA also
I found that marlin make
a juvenile form of SERCA
in their heater tissue.
Does this contribute to
heat production, or do
all vertebrates have
SERCA 1B in their eye
muscles (just because
eye muscles are weird)?
1 2 3 4 5
300 bp
Tyson Cramer showed that
rats make 1A (adult version)but chickens make 1B;
so not all verts have 1B in
eye muscle.
15-13, 593
Na+/K+ ATPase-another well-studied pump
BLOCKED BY
OABAIN
Km=.2 mM
vs. 4 mM
outside (K+)
Km=.6 mM
vs. 12 mM
inside
(Na+)
p. 648
V-type pumps move protons against their concentration
gradient-used to acidify vesicles (lysosome, CURL)
ATP
~5
ADP
~7
Acid-secreting cells,
like this one from toad
bladder-almost solid with
V-type pumps
15-14, 594
100 X differencecan't pump H+ forever-would
build up huge charge gradient
which would oppose any further
movement of H+
-either 1 cation out for 1 cation
in or cation in, anion out
15-16, 596
MDR, or multi-drug resistance transport protein
-ATP hydrolysis used to export small hydrophobic molecules
-activity correlated with exposure to toxins-often thwarts
efforts of chemotherapy-can be used as an indicator of exposure
to pollution
-CFTR protein, a chloride channel that is defected in cystic fibrosis
patients, is similar in structure to MDR
Group Exercise # 11
Come up with an analogy that explains how a Na+/K+ pump works.
Imagine you are explaining this to a 4th grade class.