Figure 1.

Classification of cell plasma membrane proteins. (A) Cell plasma membrane proteins can be divided in 3 general classes, namely integral membrane proteins, peripheral membrane proteins and lipid anchored proteins. (B) Integral membrane proteins can be further divided into 2 groups, namely integral monotopic proteins and transmembrane proteins. (C) Based on their topology, the family of transmembrane proteins can be classified in type I, type II, type III, type IV, β-barrel and multi-pass transmembrane proteins. (D) Multi-pass transmembrane proteins can be divided into different classes based on their function, namely transport proteins and receptors. (E) Transport proteins include channels and pores, ATP-powered pumps and 3 types of porters, namely uniporters, symporters and antiporters.