1z24
From Proteopedia
The molecular structure of insecticyanin from the tobacco hornworm Manduca sexta L. at 2.6 A resolution.
Overview
Insecticyanin, a blue biliprotein isolated from the tobacco hornworm Manduca sexta L., is involved in insect camouflage. Its three-dimensional structure has now been solved to 2.6 A resolution using the techniques of multiple isomorphous replacement, non-crystallographic symmetry averaging about a local 2-fold rotation axis and solvent flattening. All 189 amino acids have been fitted to the electron density map. The map clearly shows that insecticyanin is a tetramer with one of its molecular 2-fold axes coincident to a crystallographic dyad. The individual subunits have overall dimensions of 44 A X 37 A X 40 A and consist primarily of an eight-stranded anti-parallel beta-barrel flanked on one side by a 4.5-turn alpha-helix. Interestingly the overall three-dimensional fold of the insecticyanin subunit shows remarkable similarity to the structural motifs of bovine beta-lactoglobulin and the human serum retinol-binding protein. The electron density attributable to the chromophore is unambiguous and shows that it is indeed the gamma-isomer of biliverdin. The biliverdin lies towards the open end of the beta-barrel with its two propionate side chains pointing towards the solvent and it adopts a rather folded conformation, much like a heme.
About this Structure
1Z24 is a Single protein structure of sequence from Manduca sexta. Full crystallographic information is available from OCA.
Reference
The molecular structure of insecticyanin from the tobacco hornworm Manduca sexta L. at 2.6 A resolution., Holden HM, Rypniewski WR, Law JH, Rayment I, EMBO J. 1987 Jun;6(6):1565-70. PMID:3608987 Page seeded by OCA on Sat May 3 17:05:38 2008
