Faculty Collaboration Database

Membrane assembly in retinal photoreceptors I. Freeze-fracture analysis of cytoplasmic vesicles in relationship to disc assembly. J Cell Biol 1980 Nov;87(2 Pt 1):451-63

Date

11/01/1980

Pubmed ID

7430251

Pubmed Central ID

PMC2110759

DOI

10.1083/jcb.87.2.451

Scopus ID

2-s2.0-0019218713 (requires institutional sign-in at Scopus site)   64 Citations

Abstract

To study precursor-product relationships between cytoplasmic membranes of the inner segment of photoreceptors and the continually renewed outer disc membrane, we have compared the density and size distribution of intramembrane particles (IMP) in various membrane compartments of freeze-fractured photoreceptor inner and outer segments. Both rod and cone outer segments of Xenopus laevis are characterized by a relatively uniform distribution of approximately 4,400-4,700 IMP/micron2 in P-face (PF) leaflets of disc membranes. A similar distribution of IMP is found in the outer segment plasma membrane, the ciliary plasma membrane, and in the plasma membrane of the inner segment in the immediate periciliary region. In each case the size distribution of IMP can be characterized as unimodal with a mean diameter of approximately 10 nm. PF leaflets of endoplasmic reticulum, Golgi complex, and vesicles near the cilium have IMP with a size distribution like that in the cilium and outer segment, but with an average density of approximately 2,000/micron2. In contrast, IMP are smaller in average size (approximately 7.5 nm) in PF leaflets of inner segment plasma membrane, exclusive of the periciliary rgion. The similarity of size distribution of IMP in inner segment cytoplasmic membranes and those within the plasmalemma of the cilium and outer segment suggest a precursor-product relationship between the two systems. The structure of the vesicle-rich periciliary region and the segregation of IMP with different size distributions in this region suggest that components destined for incorporation into the outer segment exist as preformed membrane packages (vesicles) which fuse with the inner segment plasma membrane in the periciliary region. Subsequently, membrane components may be transferred to forming discs of the outer segment via the ciliary plasma membrane.

Author List

Besharse JC, Pfenninger KH

MESH terms used to index this publication - Major topics in bold

Animals
Cell Membrane
Endoplasmic Reticulum
Freeze Fracturing
Golgi Apparatus
Intracellular Membranes
Membrane Proteins
Microscopy, Electron
Photoreceptor Cells
Rod Cell Outer Segment
Xenopus laevis