The Hrs/STAM Complex in the Downregulation of Receptor Tyrosine Kinases
Authors: Komada, Masayuki; Kitamura, Naomi
Source: The Journal of Biochemistry, Volume 137, Number 1, January 2005 , pp. 1-8(8)
Publisher: Oxford University Press
Abstract:Cell surface receptor proteins that have undergone endocytosis are transported to the endosome. From the endosome, ligand-activated receptor tyrosine kinases are further transported to the lysosome for degradation, a process called “receptor downregulation.” By contrast, nutrient receptors, such as those for low-density lipoprotein and transferrin, are recycled back to the plasma membrane. Sorting of these two types of receptors occurs at the endosome, where ubiquitination of receptor proteins serves as the sorting signal. Namely, ubiquitinated receptors are incorporated into the lysosomal degradation pathway, whereas those that are not ubiquitinated are returned to the cell surface. Hrs and STAM are proteins that form a complex on the endosomal membrane. Recent studies have shown that the Hrs/STAM complex binds ubiquitin moieties and acts as sorting machinery that recognizes ubiquitinated receptors and transfers them to further sequential lysosomal sorting/trafficking processes.
Document Type: Research Article
Publication date: January 2005