Secondary Structure In Transmembrane Protein

Question

[Elisa]

Hi all,

According to you, can a transmembrane segment of a TM protein have each of the 3 states (H,E,C) of secondary structure? I mean, could alpha helix, beta strand or coil be found in the transmembrane segments of a TM protein, or are any of these states forbidden?

Thanks

Answer 1

[Lars Juhl Jensen]

The vast majority of transmembrane segments are helices, that is transmembrane helices. There is also a smaller number of transmembrane proteins that have a beta barrel structure, most notably the porins. I have never heard of transmembrane segments with coil structure, and from a biophysical perspective I find it difficult to imagine that they exist.

[Flow]

It seems that due to the environment, only helices are stable in that situation

[Lars Juhl Jensen]

I am sorry, but you are wrong. Like I wrote, there are transmembrane proteins with a beta barrel structure. In these, the transmembrane segments have extended sheet conformation.