The specific proteins or polysaccharides are located on the outer surface of plasmalemma of the cell. What is their typical function?

The specific proteins or polysaccharides are located on the outer surface of plasmalemma of the cell. What is their typical function?

1.  Phagocytosis


2.  Pinocytosis


3.  Excretion


4.  Clasmatosis


5.  *Receptor