High impact information on TLG1

• Swf1-dependent palmitoylation of the SNARE Tlg1 prevents its ubiquitination and degradation [1].
• In an swf1Delta mutant, Tlg1 is mis-sorted to the vacuole [1].
• Antibody inhibition experiments coupled with antigen competition indicated a requirement for soluble NSF attachment protein receptor (SNARE) proteins Tlg1p, Tlg2p, and Vti1p in this reaction [2].
• Localization of VFT to the Golgi requires Ypt6p, but is unaffected in gos1 and tlg1 mutants, in which late Golgi integral membrane proteins, including SNAREs, are mislocalized [3].
• An effector of Ypt6p binds the SNARE Tlg1p and mediates selective fusion of vesicles with late Golgi membranes [3].

Biological context of TLG1

• Tlg1p has been identified as a nonessential protein required for efficient endocytosis as well as the maintenance of normal levels of trans-Golgi network proteins [4].
• In this study we independently describe Tlg1p as an essential protein required for cell viability [4].
• Finally, we found that mutation of single PKA sites in Tlg1 (Ser31 to Ala31) or Tlg2 (Ser90 to Ala90) was sufficient to restore endocytosis, but not exocytosis, to snc cells [5].

Anatomical context of TLG1

• Morphological analyses by electron microscopy reveal that cells depleted of Tlg1p or tlg1 ts mutants incubated at the restrictive temperature accumulate 40- to 50-nm vesicles and experience fragmentation of the vacuole [4].
• A role for Tlg1p in the transport of proteins within the Golgi apparatus of Saccharomyces cerevisiae [4].
• Temperature-sensitive (ts) mutants of Tlg1p also accumulate the endoplasmic reticulum/cis-Golgi form of carboxypeptidase Y at the nonpermissive temperature (38 degrees C) and exhibit underglycosylation of secreted invertase [4].
• The first endocytic compartment, termed the early/recycling endosome, contains the t-SNARE, Tlg1p [6].
• Tlg1p also binds the plasma membrane v-SNARE Snc1p [7].

Physical interactions of TLG1

• We have determined the structure of the N-terminal domain of Tlg1 bound to a peptide from the N terminus of Vps51 [8].

Other interactions of TLG1

• Conversely, when Tlg1p is present, Syn8p can be removed without loss of Pep12p function, or induction of any other obvious trafficking defect [9].
• Vps51p links the VFT complex to the SNARE Tlg1p [10].
• Notably, Snc1(ala43) was found to be nonfunctional in cells lacking Tlg1 or Tlg2 [11].
• Mutation of RCY1 leads to the accumulation of an enlarged compartment that contains the t-SNARE Tlg1p and lies close to areas of cell expansion [12].
• We propose that clathrin and AP-1 act to recycle Chs3p and Tlg1p from the early endosome to the TGN [13].

References