Three-dimensional structure of recombinant type 1 inositol 1,4,5-trisphosphate receptor.
IP3Rs (inositol 1,4,5-trisphosphate receptors) are the intracellular channels that mediate release of Ca2+ from the endoplasmic reticulum in response to the many stimuli that evoke Ins(1,4,5)P3 formation. We characterized and purified type 1 IP3R heterologously expressed in Sf9 insect cells, and used the purified IP3R1 to determine its three-dimensional structure by electron microscopy and single-particle analysis. Recombinant IP3R1 has 4-fold symmetry with overall dimensions of approx. 19.5 nm x 19.5 nm x 17.5 nm. It comprises a small domain, which is likely to include the pore, linked by slender bridges to a large cytoplasmic domain with four petal-like regions. Our structures of recombinant IP3R1 and native cerebellar IP3R have similar appearances and dimensions. The only notable difference is the absence of a central stigma-like domain from the cytoplasmic region of recombinant IP3R1. The first structure of a recombinant IP3R is an important step towards developing three-dimensional structures of IP3R that better contribute to our understanding of the structural basis of IP3R activation.
Wolfram
Francis
F
Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB21PD, UK.
Morris
Edward
E
Taylor
Colin W
CW
D000818:Animals; D002478:Cells, Cultured; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D008958:Models, Molecular; D011487:Protein Conformation; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry* / Q000378:metabolism
D053496:Inositol 1,4,5-Trisphosphate Receptors; D011994:Recombinant Proteins