Chemotaxis in eukaryotic cells: a focus on leukocytes and Dictyostelium.

OVERVIEW ..................................................................................................................... 649 FEATURES OF CHEMOTACTIC BEHAVIOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650 HOW DO CELLS ACCOMPLISH CHEMOTAXIS? ..................................................................... 652 Critical Questions ............... ..................................................................................... . 652 Hypothetical Schemes for Chemotaxis ...................................................................... 652 RESPONSES INDUCED BY ADDITION OF CHEMOATTRACTANTS . . . ........... . . . . . . . . . . . . . . . . ....... . . . . . . . 656 Physiological Responses ........................................................................................... 656 Underlying Biochemistry .......................................................................................... .659 CHEMOATTRACTANT-INDUCED DESENSITIZATION ......... .................................................... 669 Receptor Alterations ................................................................................................. 669 Additional Desensitization Mechanisms .................................................................... 670 CURRENT VIEW OF EUKARYOTIC CHEMOTAXIS . . . . . . . . . . ......... . . . . . . . . . .. ...... . ........ . . . . . . ...... . . . . . . . . 672 Biochemical Events Essential for Chemotaxis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 672 Working Modelfor Chemotaxis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 672