User talk:Amulekii

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I moved your message from Splette's user page to his user talk page. User talk pages are used for communicating, and generally, we don't edit each others' user pages.

Again, welcome! Mango juice talk 04:08, 18 May 2006 (UTC)

ARP2/3 complex
Hi Amulekii, thanks for your comment. I answered it on the ARP2/3 discussion page -- Splette   Talk 13:18, 18 May 2006 (UTC)

Hi again, if its actin you want to nucleate you definately don't need ARP2/3. All you need is a solution with a sufficient G-actin concentration. When you add cations they start to nucleate. I suggest divalent cations. In vivo its usually magnesium but in solution calcium will do, too. That should be all. If you need to stabilize the filaments use phalloidin. I don't know other ways to stabilize it. Phalloidin does a good job and is toxic (because it does exactly this: preventing actin filaments from depolymerizing) but shouldn't be a problem to work with as long as you don't eat it... I don't know about other ways to stabilize them. Note that the properties of actin filaments change when you apply phalloidin e.g. their stiffness increases a lot. What exactly are you doing to be interested in this stuff? Are you doing a masters or PhD thesis with actin? Tell me a bit ... -- Splette  Talk 23:20, 18 May 2006 (UTC)

Hi Amulekii, I have a biological background but I am doing my PhD in computational biophysics now. I am doing atomic detail computer simulations of actin monomers and the filament. In my project I was supposed to collaborate with an experimental lab but that seems unlikely now as my project is taking another direction now. However, about a year ago I visited their lab to get an idea of the work (here is a paper: Roos W, Roth A, Sackmann E, Spatz JP. 2003.  Freely suspended actin cortex models on arrays of mirco-fabricated pillars.  Chem Phys Chem  4:872-877) they are doing. In a cell free environment they create actin filaments and crosslink them to form networks. They told me that it was rather easy to polymerize the actin monomers to filaments. You don't even need physiological temperature - room temperature will do. As far as I know they didn't need any special nucleators for the filaments to form just the right cation concentration. I don't know what exactly you are trying to do. While it's easy to get actin to form filaments randomly it's more difficult to control where they form and control their length. This is one of the reasons there is still no righ resolution x-ray structure of the filament, just models - they just won't crystallize. If you want to specify location and length of the filaments you may need other proteins/molecules like ARP2/3, phallidin or one of the many actin capping proteins that prevent further growing. If microtubules would be a better choice I can't tell. I hope this was helpful. Tell me a bit more about you and your project, I am curious. -- Splette  Talk 14:13, 22 May 2006 (UTC)

I think this is paper might be useful: http://www.jcb.org/cgi/reprint/93/3/648 -- Splette  Talk 12:46, 23 May 2006 (UTC)