Cell Membrane Composition

[nezva]

Do all cellular membranes have transport proteins? I ask this question in an attempt to identify some of the evolutionary difficulties the "first cell" would've experienced.

[CharonY]

Do all cellular membranes have transport proteins? I ask this question in an attempt to identify some of the evolutionary difficulties the "first cell" would've experienced.

 

I am not aware of any exceptions. Even if not actively growing, transport proteins would be required for energy conservation. One of the hall marks of living cells is their ability to create and maintain a proton gradient. For that membrane proteins are indispensable.

[kellbrook]

so transport proteins specificthings they take in and out, is it possible for something that doesn't usually go in that way,if it was bonded to something that goes in that way

 

 

[CharonY]

Depends on the transport mechanism and the substrate to be transported. Some molecules are so similar that transport systems have trouble telling them apart, and some transport are somewhat promiscuous in what they transport. However, there is always a certain selectivity in there.

[kellbrook]

i guess my specific question is about magnesium ion uptake and cell transport proteins, magnesium ion is taken into the cell through the magnesium/ATPase pathway, but i want to know if magnesium was bonded to something like an amino acid, can this (magnesium+amino acid) be taken up together through the same pathway that amino acid normally use?

 

charony i sent you pm but don't know if you got it, also how do i check to see if i recieved any pm?

 

 

Edited July 11, 2011 by kellbrook

[CharonY]

I would not know how a Mg2+ would be bound to an amino acid. I do not know any examples, but theoretically it may be possible that during AA transport (probably especially for negatively charged one) Mg2+ may be accidentally transporter in. But again, I do know of any examples.

 

If you chemically modify amino acids in a way, then it really depends on a) the specificity of the transporter and the impact of the modification of the overall structure of the ligand. But this has to be analysed on a case by case basis and involves serious modelling.

Edited July 11, 2011 by CharonY

[Joshua201]

proteins are needed for transport across a membrane