channels and transporters lecture 1 Flashcards
what are the 4 transmembrane transports mechanisms
simple diffusion, facilitated diffusion, active transport, cotransport
what are the 3 main classes of transporters
channels, transporters, ATP powered pumps.
which protein family does CFTR ion channel belong to
the ABC transporters(ATP powered pumps).
where do beta barrel pores appear
outer membrane of gram negative bacteria, chloroplasts, and mitochondria
what are the dominating outer membrane porins in E.coli
OmpF and OmpC
what type of channel are beta barrel pores
passive diffusion channels
describe the structure of OmpF and OmpC
they have little selectivity for solutes. one loop folds into the barrel which gives restriction in the middle. acidic residues in the loop give some cation specificty
which beta barrel pore does have some specificity for solutes
PhoE which transports phosphate.
what difference is there in structure of PhoE and OmpF
the constricting loop
what is LamB
beta barrel. maltose or matodextrins porins. has 3 loops with 6 aromatic residues in the pore for guided diffusion. receptor for phage
what is FepA and FhuA
they uptake siderophores. very specific. acitve uptake because of plug domain that is coupled to TonB
describe the structure of gap junctions/connexin
4 transmembrane alpha helices.6 monomers per bialyer. junction spans 2 membranes in multicellular organisms. open and close of junction is controlled by phosphorylation
what does transmembrane diffusion depend on
concentration difference. transmembrane potential. osmotic pressure.
what is GLUT1 and how does it transport glucose
first glucose transporter be discovered. transports glucose to RBC. if a mutation occurs in GLUT1 can lead to De vivo disease. they are uniporters.
what family does GLUT belong to
the major facilitator superfamily. they usually have 12 TM alpha helices. has different binding sites on either side of the membrane
