title: Three-dimensional reconstruction of a complex of human alpha 2-macroglobulin with monomaleimido Nanogold (Au1.4nm) embedded in ice.
abstract: Cysteine 949 and glutamine 952 are known to be part of the thiol ester site of each of the four subunits of human alpha 2-macroglobulin (alpha 2M). The hydrolysis of this thiol ester bound to methylamine results in the incorporation of the amine and liberation of a free sulfhydryl group that can be specifically labeled. Therefore, a high-resolution marker specific for the sulfhydryl groups, the monomaleimido Nanogold (Au1.4nm) cluster was used to bind this amino acid. After cryoelectron microscopy, a three-dimensional reconstruction of the alpha 2M-Nanogold conjugates (alpha 2M-Au1.4nm) was achieved, revealing the internal location of the thiol ester sites in the transformed alpha 2M molecules. From this study we propose three possible locations for the cysteine 949.
authors.affiliation: Laboratoire de Biochimie Fondamentale, Université François Rabelais and CNRS URA 1334, Tours, France.
authors.forename: N
authors.initials: N
authors.lastname: Boisset
authors.forename: R
authors.initials: R
authors.lastname: Grassucci
authors.forename: P
authors.initials: P
authors.lastname: Penczek
authors.forename: E
authors.initials: E
authors.lastname: Delain
authors.forename: F
authors.initials: F
authors.lastname: Pochon
authors.forename: J
authors.initials: J
authors.lastname: Frank
authors.forename: J N
authors.initials: JN
authors.lastname: Lamy
mesh_terms: D003545:Cysteine; D005615:Freezing; D005973:Glutamine; D006801:Humans; D006868:Hydrolysis; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D000511:alpha-Macroglobulins / Q000648:ultrastructure*
chemical_list: D000511:alpha-Macroglobulins; D005973:Glutamine; D003545:Cysteine