The END3 gene encodes a protein that is required for the internalization step of endocytosis and for actin cytoskeleton organization in yeast.

Abstract

Two Saccharomyces cerevisiae mutants, end3 and end4, defective in the internalization step of endocytosis, have previously been isolated. The END3 gene was cloned by complementation of the temperature-sensitive growth defect caused by the end3 mutation and the END3 nucleotide sequence was determined. The END3 gene product is a 40-kDa protein that has a putative EF-hand Ca(2+)-binding site, a consensus sequence for the binding of phosphotidylinositol 4,5-bisphosphate (PIP2), and a C-terminal domain containing two homologous regions of 17-19 aa. The EF-hand consensus and the putative PIP2-binding sites are seemingly not required for End3 protein function. In contrast, different portions of the End3p N-terminal domain, and at least one of the two repeated regions in its C-terminus, are required for End3p activity. Disruption of the END3 gene yielded cells with the same phenotype as the original end3 mutant. An end3ts allele was obtained and this allowed us to demonstrate that End3p is specifically involved in the internalization step of endocytosis. In addition, End3p was shown to be required for proper organization of the actin cytoskeleton and for the correct distribution of chitin at the cell surface.

Scd5p Mediates Phosphoregulation of Actin and Endocytosis by the Type 1 Phosphatase Glc7p in Yeast

“…This was indeed the case ( Figure 2D). Both End3⌬N and End3⌬C mutant proteins complemented the temperature sensitivity of the end3 null mutant (data not shown), as reported previously (Benedetti et al, 1994), indicating that they were expressed functionally in the cells. Since the C-terminal region of End3p was still capable of binding Pan1p (Tang et al, 1997), the role of End3p is probably more in promoting Pan1p dephosphorylation than protecting it from phosphorylation.…”

“…As shown in Figure 4A, the glc7-td mutant exhibited a grossly distorted actin cytoskeleton after a prolonged incubation at 37°C (6 h) to diminish the Glc7p protein content ( Figure 4A, center). The majority of glc7-td cells contained large and aberrant actin aggregates similar to those found in the pan1-4, scd5-1, and end3⌬ mutants (Benedetti et al, 1994;Tang and Cai, 1996;Huang et al, 2003). In contrast, the control cells (glc7-ntd) maintained a normal pattern of actin cytoskeleton after the same treatment ( Figure 4A, top), suggesting that the actin abnormalities in glc7-td cells were caused by the phosphatase depletion.…”

CART: An Hrs/Actinin-4/BERP/Myosin V Protein Complex Required for Efficient Receptor Recycling

“…In yeast, mutations in actin or fimbrin inhibit endocytosis (Kubler and Riezman, 1993). Additionally, genetic screens for mutants affecting endocytosis have revealed mutations in several genes that disrupt both endocyThis article was published online ahead of print in MBC in Press (http://www.molbiolcell.org/cgi/doi/10.1091/mbc.E04 -11-1014) on March 16, 2005. tosis and actin organization (Benedetti et al, 1994;Munn et al, 1995;Tang et al, 1997). However, some yeast mutants that disrupt actin organization have no effect on endocytosis (Riezman et al, 1997), and some suppressors of an endocytosis mutant that also affects actin organization (end5) can rescue one or the other phenotype, but not both, suggesting that they are separable (Riezman et al, 1997).…”

“…© 2005 by The American Society for Cell Biology tosis and actin organization (Benedetti et al, 1994;Munn et al, 1995;Tang et al, 1997). However, some yeast mutants that disrupt actin organization have no effect on endocytosis (Riezman et al, 1997), and some suppressors of an endocytosis mutant that also affects actin organization (end5) can rescue one or the other phenotype, but not both, suggesting that they are separable (Riezman et al, 1997).…”

Alu-splice cloning of human Intersectin (ITSN), a putative multivalent binding protein expressed in proliferating and differentiating neurons and overexpressed in Down syndrome

“…ITSN posesses two EH domains or Eps15 homology domains which are involved in protein-protein interactions and are frequently present in multiple copies. 19 Most of the EH-containing proteins, such as mammalian Eps15 20 and yeast End3p, 21 have been linked to endocytic pathways. The central part of the protein has five consecutive Src homology 3 (SH3) domains.…”