A single myosin head can be cross-linked to the N termini of two adjacent actin monomers.

Myosin subfragment-1 (S1) can be cross-linked to two actin monomers by 1-ethyl-3-[3-(dimethylamino)-propyl]-carbodiimide only when F-actin is in excess over S1. Electron micrographs of the covalent actin2-S1 complex showed that S1 was cross-linked to two adjacent monomers of the same actin filament. Cross-linking experiments with pre-proteolyzed S1 derivatives in combination with a proteolytic dissection of the intact covalent actin2-S1 adduct (m = 265 kDa), revealed that two N-terminal segments of actin (residues 1-28) were covalently attached to a single S1 molecule.

Site-directed mutagenesis of elongation factor Tu. The functional and structural role of residue Cys81.

A Cys residue located in the second consensus sequence element (DCPG) of the GTP-binding region is highly conserved in bacterial elongation factors (EF) Tu. Chemical modification of this Cys81 in EF-Tu from Escherichia coli by N-tosyl-L-phenylalanine chloromethane [Jonák, J., Petersen, T.