RESUMEN
Ionotropic glutamate receptors are major excitatory receptors in the central nervous system and also have a far reaching influence in other areas of the body. Their modular nature has allowed for the isolation of the ligand-binding domain and for subsequent structural studies using a variety of spectroscopic techniques. This review will discuss the role of specific ligand:protein interactions in mediating activation in the a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid subtype of glutamate receptors as established by various spectroscopic investigations of the GluR2 and GluR4 subunits of this receptor. Specifically, this review will provide an introduction to the insight gained from X-ray crystallography and nuclear magnetic resonance investigations and then go on to focus on studies utilizing vibrational spectroscopy and fluorescence resonance energy transfer to study the behavior of the isolated ligand-binding domain in solution and discuss the importance of specific ligand:protein interactions in the mechanism of receptor activation.
Asunto(s)
Humanos , Receptores de Glutamato/química , Transferencia de Energía , Antagonistas de Aminoácidos Excitadores/química , Antagonistas de Aminoácidos Excitadores/metabolismo , Ligandos , Espectroscopía de Resonancia Magnética , Unión Proteica , Conformación Proteica , Receptores de Glutamato/metabolismo , Espectroscopía Infrarroja por Transformada de Fourier , Relación Estructura-Actividad , /química , /metabolismoRESUMEN
Lectin activities in roots, nodules, stems and leaves of 1-6 week old peanut plant (A. hypogaea) were checked by erythrocyte (human and rabbit) agglutination and sugar inhibition assays. Human and rabbit erythrocyte agglutinating activities were specifically inhibited by lactose/cellobiose (SLII) and methyl alpha-mannoside (SLI) respectively. Seeds, embryos and cotyledons agglutinated neuraminidase treated human erythrocytes and that activity was inhibited by T-disaccharide. In the roots of field grown plants SLI was the major activity, while nodules showed both activities (SLI and SLII). Specific activities of SLI and SLII were maximal in stem tissue and hypocotyl exhibited minimal levels. Actively growing tissues like newly emerging young leaves and elongating stem contained more SLII activity in comparison to the mature tissues. Immunological test indicated that all the vegetative tissue lectins are serologically related.