title: Rapana thomasiana hemocyanin (RtH): comparison of the two isoforms, RtH1 and RtH2, at 19A and 16A resolution.
abstract: Three-dimensional (3D) reconstructions of the two 8.4 MDa Rapana thomasiana hemocyanin isoforms, RtH1 and RtH2, have been obtained by cryoelectron microscopy of molecules embedded in vitreous ice and single particle image processing. The final 3D structures of the RtH1 and RtH2 didecamers at 19 A and 16 A resolution, respectively, are very similar to earlier reconstructions of gastropodan hemocyanins, revealing structural features such as the obliquely oriented subunits, the five- and two-fold symmetrical axes. Three new interactions are defined; two of them connecting the arch and the wall while the third is formed between the collar and the wall. The collar-wall connection and one of the arch-wall connections are positioned between two individual subunit dimers, while the second arch-wall connection is located between two subunits within the subunit dimer. All three interactions establish connections to the first tier of the wall. Furthermore, for each interaction we have allocated two first tier functional units most likely involved in forming the connections.
authors.affiliation: Department of Biosciences at NOVUM, Karolinska Institutet and School of Technology and Health, Royal Institute of Technology, S-141 57 Huddinge, Sweden.
authors.forename: Kimberley
authors.initials: K
authors.lastname: Cheng
authors.forename: Philip J B
authors.initials: PJ
authors.lastname: Koeck
authors.forename: Hans
authors.initials: H
authors.lastname: Elmlund
authors.forename: Krassimira
authors.initials: K
authors.lastname: Idakieva
authors.forename: Katja
authors.initials: K
authors.lastname: Parvanova
authors.forename: Heinz
authors.initials: H
authors.lastname: Schwarz
authors.forename: Tomas
authors.initials: T
authors.lastname: Ternström
authors.forename: Hans
authors.initials: H
authors.lastname: Hebert
mesh_terms: D000818:Animals; D020285:Cryoelectron Microscopy; D006433:Hemocyanins / Q000302:isolation & purification / Q000648:ultrastructure*; D006458:Hemolymph / Q000737:chemistry; D007091:Image Processing, Computer-Assisted; D008958:Models, Molecular; D020033:Protein Isoforms / Q000302:isolation & purification / Q000648:ultrastructure; D012908:Snails / Q000737:chemistry*
chemical_list: D020033:Protein Isoforms; D006433:Hemocyanins