The eukaryotic endosomal trafficking is essential for the internalization and trafficking of macromolecules, fluid, membranes, and membrane proteins.
Nucleoporins act not only in trafficking of macromolecules but also in proper microtubule attachment to kinetochores, in the regulation of gene expression and signaling events associated with, for example, innate and adaptive immunity, development and neurodegenerative disorders.
Trafficking of macromolecules across the nuclear envelope (NE) occurs exclusively through the nuclear pore complex (NPC), a ∼100 MDa cylindrical structure with octagonal symmetry, comprising coaxial rings and a central aqueous channel.
MOS3/SAR3 encodes a nuclear membrane protein with homology to human nucleoporin 96, a subunit of a nuclear pore complex involved in nucleocytoplasmic trafficking of macromolecules (Zhang and Li, 2005).
Microtubules are involved in a diverse range of cellular functions, including motility, maintenance of cell shape, adhesion, intracellular trafficking of macromolecules and organelles, and, most importantly, mitosis [ 1- 4].
Nuclear pore complexes (NPCs) are the exclusive gateways in the NE allowing diffusion of small substances and regulated trafficking of macromolecules up to a size of 15 nm for ribosomal subunits or even 50 nm for Balbiani ring particles (for review, see Wente and Rout, 2010; Hoelz et al, 2011; Bilokapic and Schwartz, 2012).
Additionally studies have demonstrated that lectin-like proteins are able to interact with RNA molecules, are involved in the long-distance trafficking of macromolecules and may play a role in long-distance signaling in response to infection by plant pathogens [ 49, 50].
Intracellular trafficking of such macromolecules to lysosomes are mediated by the following processes: endocytosis of cell-surface-receptor proteins with bound ligands, produces early endosomes; heterophagocytosis of large extracellular materials, such as dead cells and bacteria, produces heterophagosomes; and, autophagy of old and unneeded intracellular materials produces autophagosomes.
Endothelial cells in the brain form the blood brain barrier, a specialized interface between the blood and the brain that tightly controls traffic of nutrients and macromolecules between two compartments and interacts closely with other cells forming the neurovascular unit.
The presence of α-tubulin in the syncytial tegument can be associated with requirements of MT that are necessary for maintaining the highly dynamic vesicular traffic required for uptake and secretion of macromolecules as demonstrated for T. crassiceps cysticerci [29] and are well known in eukaryotic cells [20].
