Seel proteins

Figure 46-7. Model of the steps in a round of anterograde vesicular transport. The cycle starts in the bottom left-hand side of the figure, where two molecules of ARF are represented as small ovals containing GDP. The steps in the cycle are described in the text. Most of the abbreviations used are explained in Table 46-7. The roles of Rab and Seel proteins (see text) in the overall process are not dealt with in this figure. (CGN, cis-Golgi network BFA, Brefeldin A.) (Adapted from Rothman JE Mechanisms of intracellular protein transport Nature 1994 372 55.) (Courtesy of E Degen.)...

Seel A member of a family of proteins that attach to t-SNAREs and are displaced from them by Rab proteins, thereby allowing v-SNARE-t-SNARE interactions to occur. 

It is noteworthy that there is another limiting factor in the choice of amino acid types at the junction sites which affect the enzymatic process of the intein. For example, in the case of SceVMA (also called PI-Seel) from the IMPACT system, proline, cysteine, asparagine, aspartic acid, and arginine cannot be at the C-terminus of the N-terminal target protein just before the intein sequence. The presence of these residues at this position would either slow down the N-S acyl shift dramatically or lead to immediate hydrolysis of the product from the N-S acyl shift [66]. The compatibility of amino acid types at the proximal sites depends on the specific inteins and needs to be carefully considered during the design of the required expression vectors. The specific amino acid requirements at a particular splicing site depends on the specific intein used and is thus a crucial point in this approach. 

Halachmi N, Lev Z (1996) The Seel family a novel family of proteins involved in synaptic transmission and general secretion. J Neurochem 66 889-97 Haley JE, Delmas P, Offermanns S et al (2000) Muscarinic inhibition of calcium current and M current in Galpha q-deficient mice. J Neurosci 20 3973-9 Hamid J, Nelson D, Spaetgens R et al (1999) Identification of an integration center for cross-talk between protein kinase C and G protein modulation of N-type calcium channels. J Biol Chem 274 6195-6202... 

The central limitation of the subtractive approach is that it identifies only proteins that are unique to the NE it will disregard proteins that normally occur in both of the fractions analyzed. One such protein is Seel 3, an ER trafficking protein that also has a demonstrated function in NPC mediated transport (Siniossoglou et al. 1996). Seel 3 thus appeared in both datasets and was accordingly discarded from the NE-unique in silico purified protein set. TorsinA also appeared in both datasets and was discarded, but it has since been shown to shuttle between the INM and the ER (Goodchild and Dauer 2004). As 41% of the 566 proteins identified in the membrane-enriched NE fraction were similarly discarded, there may be many other proteins listed in the pre-subtraction dataset that are truly NE proteins, though they are not unique to the NE. 

Rice, L. M., and Brunger, A. T. (1999). Crystal structure of the vesicular transport protein Seel 7 implications for SNAP function in SNARE complex disassembly. Mol. Cell 4, 85-95. 

Seeling JM et al (1999) Regulation of beta-catenin signaling by the B56 subunit of protein phosphatase 2A. Science 283 2089-2091... 

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