What type of membrane proteins have an exposed site on the outer cell surface that can attach to a ligand?

Question

Quizplus · Accepted Answer

Receptor proteins have an exposed site on the outer cell surface that can attach to a specific ligand, such as a hormone, neurotransmitter, or antigen. This binding initiates a signal transduction pathway that ultimately leads to a cellular response. Marker molecules serve as identification tags for the cell, channel proteins form pores for the passive transport of specific molecules, enzymes catalyze chemical reactions, and carrier proteins transport specific molecules across the membrane.

What Type of Membrane Proteins Have an Exposed Site on the Outer