Do peripheral proteins have both hydrophilic and hydrophobic domains?

[Transformers]

Sorry, but I thought peripheral proteins have only hydrophilic domains (i.e.- an MHC class molecule)- considering that that they would be exposed to the aq ECF medium and bind to the hydrophilic heads of the phospholipid membrane. In contrast, it makes sense to be that a transmembrane protein would have both hydrophilic and hydrophobic domains. I am just pissed that a berkeley review question said that an MHC class I and class II proteins have both domains when clearly they are exposed only on the outer leaflet of the PMembrane...

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[capn jazz]

Are they integral membrane proteins? Because if so, they're amphipathic just like phospholipids are.

 

[matth87]

Yes it has both domains.

If its peripheral it will have to H-bond to the Lipid bilayer so the out side is hydrophilic but the inside of the protein will be hydrophobic.

 

[Charles_Carmichael]

Sorry, but I thought peripheral proteins have only hydrophilic domains (i.e.- an MHC class molecule)- considering that that they would be exposed to the aq ECF medium and bind to the hydrophilic heads of the phospholipid membrane. In contrast, it makes sense to be that a transmembrane protein would have both hydrophilic and hydrophobic domains. I am just pissed that a berkeley review question said that an MHC class I and class II proteins have both domains when clearly they are exposed only on the outer leaflet of the PMembrane...

MHC proteins DO have both domains. The hydrophobic domain inserts into the cell membrane and docks the MHC there. It'd be hard for the protein to stay on the surface of the cell membrane if it wasn't anchored; it would just float away into the blood otherwise.

MHC proteins would be considered transmembrane proteins since they have a cytoplasmic domain, a transmembrane domain, and an extracellular domain. Hope this helps.