Tts1, the fission yeast homologue of the TMEM33 family, functions in NE remodeling during mitosis.
Bottom Line: An amphipathic helix located at the C-terminus of Tts1 is important for ER shaping and modulating the mitotic NPC distribution.Of interest, the evolutionarily conserved residues at the luminal interface of the third transmembrane region function specifically in promoting SPB-NE insertion.Our data illuminate cellular requirements for remodeling the NE during "closed" nuclear division and provide insight into the structure and functions of the eukaryotic TMEM33 family.
Affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 firstname.lastname@example.org email@example.com.Show MeSH
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Mentions: Sequence analyses suggest that Tts1 has four transmembrane (TM) regions in the N-terminal half of the protein, followed by a string of three α-helices exposed to the cytosol (Figure 1A; predictions of topology are consistent between www.cbs.dtu.dk/services/TMHMM/ and www.enzim.hu/hmmtop/index.php; Tusnady and Simon, 2001; C-terminal helix predictions are based on Petersen et al., 2009; www.cbs.dtu.dk/services/NetSurfP/). Sequence alignment among proteins from the eukaryotic TMEM33 family revealed two highly conserved motifs (Figure 1A; Bailey et al., 2009; http://meme.nbcr.net/meme/). One motif was found at the luminal interface of the third TM stretch, with a conserved Pro-119 and three aromatic side-chain residues (Tyr-123, His-127, and Tyr-131) predicted to lie on the same side of the helix (Figure 1A; highlighted in yellow). The other conserved, nine–amino acid motif, delimited by two tyrosines (Tyr-203 and Tyr-211), resides in the first of the three cytosolic α-helices (Figure 1A). The positively charged residues (Arg-208/210) within this motif are conserved in fungi (Figure 1A). Although not conserved outside the fission yeast clade, the third C-terminal helix from Val-240 to Ala-257 (VIKNAWHTFKTYVSKFGA) is predicted to exhibit amphipathic properties (Figure 1A; Gautier et al., 2008; http://heliquest.ipmc.cnrs.fr/).
Affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 firstname.lastname@example.org email@example.com.