New type of protein-protein interaction

[Vladimir Matveev]

V. V. Matveev
Evidence of a New Type of Protein-Protein Interaction: Desensitized Actomyosin Blocks Ca2+-Sensitivity of the Natural One. A Possible Model for an Intracellular Signalling System Related to Actin Filaments
Physiol. Chem. Phys. & Med. NMR (2000) 32:167-178
http://www.actomyosin.spb.ru/matveev2000.htm

Abstract: Actin filaments are certainly believed to function as an intracellular signalling system; however, this is not confirmed by direct evidence. We used a two-layer actomyosin gel with a concen tration gradient of the troponin-tropomyosin complex (TT-complex, Ca2+-sensitive system) between the two layers. To prepare one layer of the system, natural actomyosin (nАМ) rich in TT-complex was used. To prepare the second layer, we used desensitized actomyosin (dAM) without the complex. All experimental studies were made in medium with a low ionic strength. Two phenomena were ob served: (1) dAM blocks Ca2+-sensitivity of nAM when the dAM weight portion in the system (as well as in mixed nAM+dAM suspension) reaches 40% and more; further increase of the dAM portion does not affect the Ca2+-sensitivity; (2) it was electrophoretically shown that a rapid diffusion of the TT-complex from nAM gel into the dAM gel took place. The apparent diffusion coefficient for the TT-complex in dAM gel is about (1-4)·10-4 cm2/sec, i.e. three orders higher than the same values for pro tein diffusion in water.

Source: http://www.ncbi.nlm.nih.gov/pubmed/11383138

[Vladimir Matveev]

Another evidences of high mobility of proteins in condensed medium
Phair RD, Misteli T. High mobility of proteins in the mammalian cell nucleus.
Nature 404 (6778): 604-609, 2000

Abstract: The mammalian cell nucleus contains numerous sub-compartments, which have been implicated in essential processes such as transcription and splicing(1,2). The mechanisms by which nuclear compartments are formed and maintained are unclear. More fundamentally, it is not known how proteins move within the cell nucleus. We have measured the kinetic properties of proteins in the nucleus of living cells using photobleaching techniques. Here we show that proteins involved in diverse nuclear processes move rapidly throughout the entire nucleus. Protein movement is independent of energy, which indicates that proteins may use a passive mechanism of movement. Proteins rapidly associate and dissociate with nuclear compartments. Using kinetic modelling, we determined residence times and steady-state fluxes of molecules in two main nuclear compartments. These data show that many nuclear proteins roam the cell nucleus in vivo and that nuclear compartments are the reflection of the steady-state association/dissociation of its 'residents' with the nucleoplasmic space. Our observations have conceptual implications for understanding nuclear architecture and how nuclear processes are organized in vivo.

Source: http://www.ncbi.nlm.nih.gov/pubmed/10766243

[freeztar]

Hello Vladimir.

Your title is a bit misleading as both articles are from 2000 which is not exactly new.

Also, as this is primarily a discussion forum, it's good to pose a question or propose a topic in such a way that it stimulates discussion.

Furthermore, please cite your sources. I understand that you're new and you can't post links until over 10 posts, but you are over that limit now and should be able to post links.

[Vladimir Matveev]

Thanks freeztar. The article is not new but the phenomenon is new one. I try to attract attention to it...

[Vladimir Matveev]

Dear freeztar:

Main points of my article:

1. Fixedly bound proteins are able however to move fast in condensed protein matrix in certain conditions.
2. ATP energy is not needed for the movement.
3. Some weight/weight ratio between gels is needed to initiate the movement.

Please be so kind to explain why the title "is a bit misleading". Thanks in advance.