NeurochemistryChick kainate binding protein lacks GTPase activityTasca, Carla I.3; Burgos, Javier S.1; Barat, Ana1; Souza, Diogo O.2; Ramírez, Galo1,4Author Information 1Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma, Cantoblanco, E-28049, Madrid, Spain 2Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 (Anexo), 90035-003 Porto Alegre, RS, Brazil 3Departamento de Bioquímica, CCB, Universidade Federal de Santa Catarina, Trindade, 88040-900 Florianópolis, SC, Brazil. 4Corresponding Author: Galo Ramírez ACKNOWLEDGEMENTS: The work was supported by the Dirección General de Enseñanza Superior e Investigación Ramón Areces (G.R.). Dr. Tasca's stay in Madrid was supported by the PDEE Program (CAPES, Brazil). D.O.S. was the recipient of a Sabbatical Professorship Award from the Fundación BBV, Spain. Received 12 April 1999; accepted 2 May 1999 NeuroReport: June 23rd, 1999 - Volume 10 - Issue 9 - p 1981-1983 Buy Abstract CHICK kainate binding protein was solubilized from cerebellar membranes and purified (×19) by use of two chromatographic steps. Measurements of [3H]kainate binding and GTPase activity in the different fractions reveal a consistent decrease of GTPase activity as the purification proceeds so that no GTPase is detectable after the final purification step. This fact, in the context of the differential involvement in nucleotide recognition of some critical amino acid residues in the p-loop motif of GTPases and in the guanine nucleotide-binding sequence of ionotropic glutamate receptors, together with significant discrepancies concerning the activity of individual nucleotides, suggests that both guanine nucleotide-recognizing sequences are unlikely to be alternative expressions of the same functional domain. © 1999 Lippincott Williams & Wilkins, Inc.