Biogenesis and Function of Late Endosomes and Lysosomes

Endocytosis is a process of internalization of extracellular fluid or cell surface receptors via diverse cell surface invaginations, generating an endosomal membrane system (Conner and Schmid 2003, Gruenberg, 2001, Gruenberg and Maxfield 1995, Guha et al. 2003, Mellman et al. 1986, Mukherjee et al. 1997, Sharma et al. 2002). It plays an important role in uptake of nutrients, scavenging of extracellular material, internalization of receptor bound ligands such as growth factors, hormones, lipoproteins and antibodies (Mellman et al. 1986, Mukherjee et al. 1997). Following internalization macromolecules are located in membrane bound vesicles referred to as endosomes.