Cell adhesion molecule L1 in folded (horseshoe) and extended conformations.
Mol Biol Cell
; 12(6): 1765-73, 2001 Jun.
Article
in En
| MEDLINE
| ID: mdl-11408583
ABSTRACT
We have investigated the structure of the cell adhesion molecule L1 by electron microscopy. We were particularly interested in the conformation of the four N-terminal immunoglobulin domains, because x-ray diffraction showed that these domains are bent into a horseshoe shape in the related molecules hemolin and axonin-1. Surprisingly, rotary-shadowed specimens showed the molecules to be elongated, with no indication of the horseshoe shape. However, sedimentation data suggested that these domains of L1 were folded into a compact shape in solution; therefore, this prompted us to look at the molecules by an alternative technique, negative stain. The negative stain images showed a compact shape consistent with the expected horseshoe conformation. We speculate that in rotary shadowing the contact with the mica caused a distortion of the protein, weakening the bonds forming the horseshoe and permitting the molecule to extend. We have thus confirmed that the L1 molecule is primarily in the horseshoe conformation in solution, and we have visualized for the first time its opening into an extended conformation. Our study resolves conflicting interpretations from previous electron microscopy studies of L1.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Membrane Glycoproteins
/
Neural Cell Adhesion Molecules
Limits:
Humans
Language:
En
Journal:
Mol Biol Cell
Journal subject:
BIOLOGIA MOLECULAR
Year:
2001
Document type:
Article
Affiliation country:
Estados Unidos