Handling Copper: A Paradigm for the Mechanisms of Metal Ion Homeostasis - Environmental Contamination: Health Risks and Ecological Restoration - page 269

Met motifs

N

Membrane

Cytosol

Cys/His motif

(A) C

ATP binding
domain

DKTGT
domain

Heavy metal
binding domain

Phosphatase
domain

Heavy metal
binding domain

N

C

Cytosol

C
P
X

Membrane

(B)

FIGURE 13.1
Schematic.diagrams.showing.the.Ctr.family.of.transporters.in.yeast.(Panel.A).and.the.HMA.
family.of.P 1B -type.ATPase.transporters.in. Arabidopsis .(Panel.B).

metal. binds. to. the. transporter,. ATP. is. utilized. for. phosphorylation. that.
changes.the.conformation.of.the.protein.resulting.in.the.translocation.of.an.
ion.across.the.membrane.(Arguello.et.al..2007)..The.P-type.ATPase.super-
family.transporters.are.not.only.found.on.cell.membranes.but.also.within.
the. cell. in. organelle. membranes,. speciically. the. Golgi. complex. and. the.
chloroplast.
Lastly. in. Gram-negative. bacteria,. there. is. an. eflux. pump. used. to. trans-
port.copper.out.of.cells..The.four-component.pump.found.in. Escherichia coli .
spans.the.inner.membrane,.periplasm,.and.outer.membrane..Since. E. coli .is.
thought.to.diffuse.Cu(I).through.its.cell.membrane,.these.bacteria.have.most.
likely.evolved.this.periplasmic.export.system.as.a.defense.to.copper.toxicity.
(Rensing.and.Grass.2003).
In. addition. to. transporters,. organisms. also. have. proteins. that. shuttle.
Cu(I). from. one. place. to. another. within. the. cell,. called. metallochaperones..
Unlike.other.chaperones,.these.proteins.do.not.aid.in.protein.folding.(Pufahl.
et. al.. 1997).. Instead,. metallochaperones. for. copper. (referred. to. as. copper.