Structural features of the terminal loop region of frog retinal rod outer segment disk membranes: II. Organization of the terminal loop complex.

Published

Journal Article

In addition to a lipid bilayer component (Corless, Fetter, and Costello: J. Comp. Neurol. 257:1-8, '87), the terminal loop region of frog rod outer segment (ROS) disks displays a clustering of discrete elements referred to as the terminal loop complex. It consists of (1) semicircular or crescentic densities within the terminal loop, (2) linear interdisk densities spanning the cytoplasm near terminal loops, and (3) distinctive freeze-fracture particles associated with the terminal loop, located between 1 and 2. The linear interdisk densities are organized on a two-dimensional lattice that appears to ensheath completely the lamellar domains of all ROS disks. Indirect evidence is presented for a net axial alignment of intraloop densities. We interpret the large freeze-fracture particles of the terminal loop region to reflect transmembrane components that connect the interdisk and intraloop densities. Thus, we propose that the entire terminal loop (TL) complex is organized on a two-dimensional net. We further infer that each TL complex is organized as a dimeric unit and that such dimers interact axially and laterally to generate the observed lattice structure. It is suggested that one component of the terminal loop complex is the high molecular weight protein localized along the disk perimeter by Papermaster, Schneider, Zorn, and Kraehenbuhl (J. Cell. Biol. 78:415-425, '78).

Full Text

Duke Authors

Cited Authors

  • Corless, JM; Fetter, RD; Zampighi, OB; Costello, MJ; Wall-Buford, DL

Published Date

  • March 1, 1987

Published In

Volume / Issue

  • 257 / 1

Start / End Page

  • 9 - 23

PubMed ID

  • 2437163

Pubmed Central ID

  • 2437163

International Standard Serial Number (ISSN)

  • 0021-9967

Digital Object Identifier (DOI)

  • 10.1002/cne.902570103

Language

  • eng

Conference Location

  • United States