Structural studies of the neural-cell-adhesion molecule by X-ray and neutron reflectivity.
The structures of adhesion proteins play an important role in the formation of intercellular junctions and the control of intermembrane spacing. This paper describes the combination of neutron and X-ray specular reflectivity measurements to investigate the structure of the ectodomain of the neural-cell-adhesion molecule (NCAM). The measurements with unmodified NCAM suggest the presence of a bend in the extracellular region. Measurements with the polysialic-acid-modified form of NCAM reveal that, at physiological ionic strength, the carbohydrate chains extend beyond the range of the unmodified protein. The excluded volume of the polymer is also ionic-strength-dependent, as expected for a polyelectrolyte. The structural characteristics obtained from these independent analyses of X-ray and neutron reflectivity data agree with each other, with prior reflectivity studies, and with molecular dimensions obtained from direct-force measurements. These results provide structural insights into the configuration of the NCAM ectodomain and the regulation of NCAM adhesion by post-translational modification.
Johnson
Colin P
CP
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Fragneto
Giovanna
G
Konovalov
Oleg
O
Dubosclard
Virginie
V
Legrand
Jean-Francois
JF
Leckband
Deborah E
DE
D000818:Animals; D002021:Buffers; D016466:CHO Cells; D006224:Cricetinae; D017666:Deuterium Oxide / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry* / Q000378:metabolism; D009502:Neutrons; D017434:Protein Structure, Tertiary; D012794:Sialic Acids / Q000737:chemistry / Q000378:metabolism; D012965:Sodium Chloride / Q000737:chemistry; D013057:Spectrum Analysis / Q000379:methods; D020349:Surface Plasmon Resonance; D014162:Transfection; D014965:X-Rays
D002021:Buffers; D008051:Lipid Bilayers; D019006:Neural Cell Adhesion Molecules; D012794:Sialic Acids; C021319:polysialic acid; D012965:Sodium Chloride; D017666:Deuterium Oxide