Actin and endocytosis in budding yeast.
Bottom Line: Many critical aspects of the CME mechanism are conserved from yeast to mammals and were first elucidated in yeast, demonstrating that it is a powerful system for studying endocytosis.In this review, we describe our current mechanistic understanding of each step in the process of yeast CME, and the essential roles played by actin polymerization at these sites, while providing a historical perspective of how the landscape has changed since the preceding version of the YeastBook was published 17 years ago (1997).Finally, we discuss the key unresolved issues and where future studies might be headed.
Affiliation: Brandeis University, Department of Biology, Rosenstiel Center, Waltham, Massachusetts 02454 email@example.com firstname.lastname@example.org.Show MeSH
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Mentions: NPFs directly associate with Arp2/3 complex and actin and serve as cofactors in stimulating nucleation. As mentioned above, there are four known NPFs in yeast: (1) Las17/WASP, (2) myosin I (Myo3 or Myo5) in a complex with Vrp1/WIP, (3) Pan1/Intersectin, and (4) Abp1 (Winter et al. 1999; Evangelista et al. 2000; Lechler et al. 2000; Duncan et al. 2001; Goode et al. 2001) (Figure 6). Each of these NPFs localizes to actin patches, binds to actin and to Arp2/3 complex, stimulates Arp2/3 nucleation activity to some degree in vitro, and exhibits genetic interactions with Arp2/3 complex and/or other NPFs. Las17/WASP and myosin I (with Vrp1) are categorized as class I NPFs because they bind actin monomers and have strong NPF effects (Sun et al. 2006). Pan1 and Abp1 are categorized as class II NPFs because they bind to F-actin and have comparably weak NPF effects (Figure 6C). Consistent with this classification, Arp2/3-inactivating mutations in Las17 combined with mutations in either myosin I or Vrp1 are synthetic lethal, demonstrating that class I NPF function is essential (Evangelista et al. 2000; Lechler et al. 2000). The roles of Pan1 and Abp1 in regulating Arp2/3 complex during endocytosis are less well understood (see below).
Affiliation: Brandeis University, Department of Biology, Rosenstiel Center, Waltham, Massachusetts 02454 email@example.com firstname.lastname@example.org.