Three-dimensional structure of Brush Border Myosin-I at approximately 20 A resolution by electron microscopy and image analysis.
Brush Border Myosin-I (BBMI) is a single-headed, unconventional myosin found in the microvilli of intestinal epithelial cells where it forms lateral bridges between the core bundle of actin filaments and the plasma membrane of the microvillus. A three-dimensional (3D) reconstruction of BBMI was made from images of negatively stained, two-dimensional (2D) crystals grown on lipid monolayers formed from mixtures of phosphatidylserine and phosphatidylcholine. The resolution of the 3D map extends to approximately 20 A and allows identification of all of the major structural domains of BBMI. The BBMI molecule is composed of three domains: a globular motor domain, a light-chain-binding domain and a lipid-binding domain. In our map, the putative motor domain is connected to an extended density, which we believe to be the light-chain-binding domain. This long, narrow region has three distinct bends, which may delineate the bound calmodulin light chains. Following the last calmodulin there is density which extends for a short distance across the lipid surface and is presumably the carboxy-terminal lipid-binding domain.
Jontes
J D
JD
Department of Cell Biology, MB25, The Scripps Research Institute, La Jolla, CA 92037, USA.
Milligan
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002147:Calmodulin / Q000378:metabolism; D002645:Chickens; D018360:Crystallography, X-Ray; D007091:Image Processing, Computer-Assisted; D008051:Lipid Bilayers; D008854:Microscopy, Electron; D008871:Microvilli / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009218:Myosins / Q000737:chemistry* / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation
D002147:Calmodulin; D008051:Lipid Bilayers; D010743:Phospholipids; D009218:Myosins