plasma membrane to endosome transport

Definition

Target type: biologicalprocess

Transport of a vesicle from the plasma membrane to the endosome. [GOC:jid]

Plasma membrane to endosome transport is a crucial process in eukaryotic cells, enabling the internalization and sorting of various molecules, including nutrients, signaling receptors, and pathogens. This intricate pathway involves a series of steps orchestrated by specific proteins and lipids, ensuring efficient and selective delivery of cargo to appropriate cellular compartments.

The journey begins with the invagination of the plasma membrane, forming a pocket-like structure known as an early endosome. This invagination is triggered by the binding of specific ligands to their receptors on the cell surface, initiating the recruitment of adaptor proteins and coat proteins. Clathrin, a major coat protein, assembles into a lattice-like structure around the invaginating membrane, contributing to the formation of a clathrin-coated pit. Other coat proteins, such as AP-2, assist in the selection and recruitment of specific cargo molecules, including receptors and their bound ligands.

As the clathrin-coated pit deepens, it eventually pinches off from the plasma membrane, forming a clathrin-coated vesicle. This vesicle then detaches from the plasma membrane and begins its journey towards the early endosome, a sorting station within the cell. The clathrin coat is rapidly disassembled, and the vesicle fuses with the early endosome, delivering its cargo.

Inside the early endosome, the cargo undergoes further sorting and processing. This sorting involves a complex interplay of different mechanisms, including pH-dependent dissociation of ligands from their receptors, interactions with sorting signals embedded in the cargo molecules, and the recruitment of specific adaptor proteins.

The early endosome serves as a hub for sorting cargo molecules into different pathways. Some cargo, such as transferrin receptors, are recycled back to the plasma membrane. Others, such as epidermal growth factor receptors, are directed to lysosomes for degradation. The fate of the cargo is determined by various factors, including the nature of the cargo itself, the presence of specific sorting signals, and the activity of sorting machinery.

In addition to the clathrin-mediated pathway, other mechanisms contribute to plasma membrane to endosome transport. Caveolae, small invaginations of the plasma membrane enriched in cholesterol and sphingolipids, can also internalize cargo. This pathway is often involved in the uptake of lipids and cholesterol, as well as certain signaling molecules.

The process of plasma membrane to endosome transport is highly regulated and dynamic, ensuring the proper trafficking and fate of a diverse array of molecules. This essential pathway plays a pivotal role in various cellular functions, including signal transduction, nutrient uptake, immune responses, and pathogen defense.'
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Proteins (1)

Compounds (3)