Endocytosis

related topics
{acid, form, water}
{disease, patient, cell}
{specie, animal, plant}
{line, north, south}

Endocytosis is the process by which cells absorb molecules (such as proteins) by engulfing them. It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane. The process opposite to endocytosis is exocytosis. [1]

Contents

Endocytosis pathways

Endocytosis pathways could be subdivided into four categories: namely, clathrin-mediated endocytosis, caveolae, macropinocytosis, and phagocytosis.[2]

  • Clathrin-mediated endocytosis is mediated by small (approx. 100 nm in diameter) vesicles that have a morphologically characteristic crystalline coat made up of a complex of proteins that mainly associated with the cytosolic protein clathrin. Clathrin-coated vesicles (CCVs) are found in virtually all cells and from domains of the plasma membrane termed clathrin-coated pits. Coated pits can concentrate large extracellular molecules that have different receptors responsible for the receptor-mediated endocytosis of ligands, e.g. low density lipoprotein, transferrin, growth factors, antibodies and many others.
  • Caveolae are the most common reported non-clathrin coated plasma membrane buds, which exist on the surface of many, but not all cell types. They consist of the cholesterol-binding protein caveolin (Vip21) with a bilayer enriched in cholesterol and glycolipids. Caveolae are small (approx. 50 nm in diameter) flask-shape pits in the membrane that resemble the shape of a cave (hence the name caveolae). They can constitute up to a third of the plasma membrane area of the cells of some tissues, being especially abundant in smooth muscle, type I pneumocytes, fibroblasts, adipocytes, and endothelial cells.[3] Uptake of extracellular molecules is also believed to be specifically mediated via receptors in caveolae.

Full article ▸

related documents
Phenol
Hydroxide
Cytoplasm
Conjugate acid
Protein synthesis
Chloride
Apatite
Lignite
Restriction enzyme
Adenine
Plasma ashing
Lysine
Hemerythrin
Supersaturation
Pyrimidine
Peroxidase
Selenocysteine
Syenite
Einsteinium
Aspartic acid
Hexane
Transmembrane receptor
Gram-positive bacteria
Critical temperature
Serine
Coordinate covalent bond
Halotolerance
SH3 domain
Metallocene
Aldehyde