New type of protein-protein interaction

[Vladimir Matveev]

I have discovered a new phenomenon---new type of protein-protein interaction demonstrated by actomyosin gels. It may play important role in cell signalling and muscle contraction. I look for a support to continue this research. The phenomenon is described in my article

"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". Physiological Chemistry Physics & Medical NMR, 32: 167-179, 2000.

(For full text and other details see my home page: http://www.actomyosin.narod.ru

Abstract: Actin filaments are certainly believed to function as an intracellular signalling system; however, this is not confirmed by direct evidence. New properties of actomyosin were found, which might help solving this problem. We used a two-layer actomyosin gel with a concen­tration gradient of the troponin-tropomyosin complex (TT-complex, Ca2+-sensitive system) between the two layers. To prepare one layer of the system, natural actomyosin (nAM) rich in TT-complex was used. To prepare the second layer, we used desensitized actomyosin (dAM) without the complex. All experiments were performed in the medium with a low ionic strength. Three phenomena were observed: (1) dAM blocks Ca2+-sensitivity of nAM when the dAM weight portion in the system (as well as in the mixed nAM+dAM suspension) reaches 40% and more; further increase of the dAM portion does not affect the Ca2+-sensitivity; (2) This interaction begins at a definite nAM/dAM threshold (critical) ratio; (3) it was electrophoretically shown that a rapid diffusion of the TT-complex from the nAM gel into the dAM gel took place. The apparent diffusion coefficient for the TT-complex in the dAM gel is about (1-4)·10-4 cm2/sec, i.e. three orders higher than the same values for protein diffusion in water. Additions to a two-component suspension of ethanol or n-propanol restore the Ca2+-sensitivity of nAM blocked by 40% dAM. CONCLUSIONS: (i) the studied protein complexes interact in the gel state; (ii) the interaction begins at a surface of interacting gel particles and extends over the entire gel volume; (iii) the interaction of actomyosin gels reversibly disturbs normal operation of the Ca2+-sensitivity system and can change the TT-complex distribution in the whole gel volume.

Home page of the project and full text see here: http://www.actomyosin.narod.ru