2 IDENTICAL HYDROPHOBIC CLUSTERS ARE PRESENT ON THE SAME ACTIN MONOMER - INTERACTION BETWEEN ONE MYOSIN SUBFRAGMENT-1 AND 2 ACTIN MONOMERS

Two-dimensional hydrophobic clusters analysis (HCA) was used to compar e the distribution of hydrophobic clusters along various actin sequenc e. HCA-deduced patterns were not altered by amino-acid variations thro ughout the evolution of actin and we observed similar hydrophobic moti fs comprising myosin subfragment-1 ATP-independent binding sites. HCA suggested the presence of two groups of identical hydrophobic motifs ( A(1) and A(2)) which bound on each side of the S1 (63 kDa-31 kDa) conn ecting segment in relation with two actin monomers. This connection is important in communications between actin- and nucleotide-binding sit es. We postulate that some relation and message between the two motifs A(1) and A(2) take place through myosin subfragment-1 (63 kDa-31 kDa) connecting segment.