Synergistic control of cellular adhesion by transmembrane 9 proteins.
The transmembrane 9 (TM9) family of proteins contains numerous members in eukaryotes. Although their function remains essentially unknown in higher eukaryotes, the Dictyostelium discoideum Phg1a TM9 protein was recently reported to be essential for cellular adhesion and phagocytosis. Herein, the function of Phg1a and of a new divergent member of the TM9 family called Phg1b was further investigated in D. discoideum. The phenotypes of PHG1a, PHG1b, and PHG1a/PHG1b double knockout cells revealed that Phg1a and Phg1b proteins play a synergistic but not redundant role in cellular adhesion, phagocytosis, growth, and development. Complementation analysis supports a synergistic regulatory function rather than a receptor role for Phg1a and Phg1b proteins. Together, these results suggest that Phg1 proteins act as regulators of cellular adhesion, possibly by controlling the intracellular transport in the endocytic pathway and the composition of the cell surface.
Benghezal
Mohammed
M
Université de Genève, Centre Médical Universitaire, Département de Morphologie, CH-1211 Geneva, Switzerland. mohammed.benghezal@medecine.unige.ch
Cornillon
Sophie
S
Gebbie
Leigh
L
Alibaud
Laeticia
L
Brückert
Franz
F
Letourneur
François
F
Cosson
Pierre
P
D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology; D004023:Dictyostelium / Q000254:growth & development / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D010587:Phagocytosis / Q000502:physiology*; D015800:Protozoan Proteins / Q000378:metabolism* / Q000502:physiology; D017386:Sequence Homology, Amino Acid
D008565:Membrane Proteins; D015800:Protozoan Proteins