Which term describes proteins that are attached to the membrane surface, not embedded in it?

Which term describes proteins that are attached to the membrane surface, not embedded in it?

• A. Peripheral proteins
• B. Integral proteins
• C. Channel proteins
• D. Transport proteins

Answer: (A)

Proteins on membranes can be categorized by where they sit relative to the lipid bilayer. The ones that are attached to the membrane surface sit on the outside or inside of the membrane rather than diving into the hydrophobic core. These are called peripheral proteins. They bind to the polar head groups of lipids or to other membrane proteins through electrostatic or hydrogen-bond interactions, so they stay on the surface and can be removed without disrupting the membrane itself. Because they don’t cross the hydrophobic interior, they’re not embedded in the bilayer. In contrast, integral proteins are embedded and often span the membrane; channel and transport proteins are typically integral because their roles require forming passageways through the membrane. So, the term describing proteins attached to the surface is peripheral proteins.

Proteins on membranes can be categorized by where they sit relative to the lipid bilayer. The ones that are attached to the membrane surface sit on the outside or inside of the membrane rather than diving into the hydrophobic core. These are called peripheral proteins. They bind to the polar head groups of lipids or to other membrane proteins through electrostatic or hydrogen-bond interactions, so they stay on the surface and can be removed without disrupting the membrane itself. Because they don’t cross the hydrophobic interior, they’re not embedded in the bilayer. In contrast, integral proteins are embedded and often span the membrane; channel and transport proteins are typically integral because their roles require forming passageways through the membrane. So, the term describing proteins attached to the surface is peripheral proteins.