Antibody decoration of neurofilaments.

Abstract

We have decorated neurofilaments with antibodies against three polypeptides (designated here as H [mol wt = 195,000], 45[mol wt = 145,000], and 46[mol wt = 73,000]) in an effort to understand the arrangement of these polypeptides within neurofilaments. The three polypeptides were purified and antibodies were raised against each. The cross-reactivity of the antibodies suggested that each polypeptide contains both shared and unique antigenic determinants. The differential reactivities of each antibody preparation were enhanced by adsorption with the two heterologous polypeptides, and the resulting preparations were used to decorate purified neurofilaments, which were then negatively stained and examined in an electron microscope. The appearance of the antibody-decorated structures led to the following conclusions: All three polypeptides are physically associated with the same neurofilament. However, the disposition of H and 46 within a filament is different; 46 antigens appear to be associated with a "central core" of the filament, whereas H antigens compose a structure more loosely and peripherally attached to the central core and periodically arranged along its axis. The antibody-decorated H-containing structure assumes variable configurations; in some cases it appears asa bridge connecting two filaments; in other cases it appears as a helix wrapping the central core with a period of approximately 1,000 A and an apparent unit length of approximately 1.5 periods. These configurations suggest several functional implications, including the possibility that H is a component of the cross-bridges observed between filaments in situ. We also note that the central core-helix relationship could be used in the design of an intracellular transport motor.

Dynamics of neuronal intermediate filaments: A developmental perspective

“…Although it has never been demonstrated directly, most neurofilaments in the mature neuron are presumed to be in the triplet subunit form [Willard and Simon, 1981;Hirokawa et al, 1984;Trojanowski et al, 19861. Indeed, the reversible assembly of class 111 intermediate filament subunits and NF-L homopolymers in vitro [Angelides et al, 19891 contrasts with the apparent in vitro and in vivo stability of the neurofilaments composed of all three subunits.…”

Axonal transport of the cytoplasmic matrix.

“…The neurofilament cross-bridges are formed from regions of the neurofilament subunits that extend out from the primary structure of the neurofilament (65). In particular, the 200,000-dalton subunit of the neurofilament triplet has been shown to contribute to these crossbridges.…”

Correlation between immune response and CNS regeneration in vertebrate phylogenesis

“…The sera of intact rabbits, tested by immunoelectrophoresis against a protein extract of spinal cord prepared according to Willard & Simon (1981), did not show precipitation lines. At two-three days after the spinal cord transection, a precipitation line appeared and persisted until survival day 21.…”