Replicated daughter chromosomes in Escherichia coli move nonprogressively and abruptly from midcell toward the quarter positions at the early D (division) period. The chromosome positioning is controlled by the mukA and mukB gene products. The mukA (tolC) gene encodes an outer membrane protein. Sequencing results of the mukB gene suggest that the MukB protein (177kDa) has 5 distinct secondary structural domains, and two MukB protein molecules from ca homodimer in coiled-coil regions, like myosin and kinesin of eukaryotic cells. MukB may provide the force required for the chromosome positioning and the amino terminal globular domain cntaining an ATP binding sequence may act as a "motor" domain.