Depolarization-induced change in the enzymatic radio-iodination of a protein on the internal surface of the squid giant axon membrane

Gainer, Harold; Carbone, Emilio; Singer, Irwin; Sisco, Kenneth L.; Tasaki, Ichiji

doi:10.1016/0300-9629(74)90011-5

Cited by 17 publications

(6 citation statements)

References 9 publications

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“…One interesting possibility is that the synthesis and transfer of proteins in the giant fiber is related to the electrical activity of the axon (17). This possibility is made even more intriguing by the observation that the adaxonal glial cells of the giant axon are hyperpolarized by axonal action potentials and that this hyperpolarization may be mediated by aeetylcholine (68,69).…”

Section: Modulation Of Local Axonal Protein Synthesis and Transfermentioning

confidence: 99%

Cell-to-cell transfer of glial proteins to the squid giant axon: The glia- neuron protein transfer hypothesis

Lasek¹,

Gainer²,

Barker³

1977

The Journal of Cell Biology

186

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The hypothesis that glial cells synthesize proteins which are transferred to adjacent neurons was evaluated in the giant fiber of the squid (Loligo pealei). When giant fibers are separated from their neuron cell bodies and incubated in the presence of radioactive amino acids, labeled proteins appear in the glial cells and axoplasm. Labeled axonal proteins were detected by three methods: extrusion of the axoplasm from the giant fiber, autoradiography, and perfusion of the giant fiber. This protein synthesis is completely inhibited by puromycin but is not affected by chloramphenicol. The following evidence indicates that the labeled axonal proteins are not synthesized within the axon itself. (a) The axon does not contain a significant amount of ribosomes or ribosomal RNA. (b) Isolated axoplasm did not incorporate [aH]leucine into proteins. (c) Injection of RNase into the giant axon did not reduce the appearance of newly synthesized proteins in the axoplasm of the giant fiber. These findings, coupled with other evidence, have led us to conclude that the adaxonal glial cells synthesize a class of proteins which are transferred to the giant axon. Analysis of the kinetics of this phenomenon indicates that some proteins are transferred to the axon within minutes of their synthesis in the glial cells. One or more of the steps in the transfer process appear to involve Ca ++, since replacement of extracellular Ca ++ by either Mg § or Co §247 significantly reduces the appearance of labeled proteins in the axon. A substantial fraction of newly synthesized glial proteins, possibly as much as 40%, are transferred to the giant axon. These proteins are heterogeneous and range in size from 12,000 to greater than 200,000 daltons. Comparisons of the amount of amino acid incorporation in glia cells and neuron cell bodies raise the possibility that the adaxonal glial cells may provide an important source of axonal proteins which is supplemental to that provided by axonal transport from the cell body. These findings are discussed with reference to a possible trophic effect of glia on neurons and metabolic cooperation between adaxonal glia and the axon.It has often been suggested that adjacent cells communicate with one another via the actual intercellular transfer of molecules including macromolecules. The possibility that molecular transfer may play a role in intercellular regulation has taken on added credibility since the discovery and

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Section: Modulation Of Local Axonal Protein Synthesis and Transfermentioning

confidence: 99%

Cell-to-cell transfer of glial proteins to the squid giant axon: The glia- neuron protein transfer hypothesis

Lasek¹,

Gainer²,

Barker³

1977

The Journal of Cell Biology

186

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“…Note that a 12,000-dalton labeled protein was released by potassium depolarization. (Gainer et al, 1974;Takenaka et al, 1976) in which membrane labeling was done by radio-iodination.…”

Section: Induction Of Protein Release From Membrane By Potassium Depomentioning

confidence: 99%

“…In an earlier investigation (Gainer et al, 1974), the proteins in the internal membrane surface of the squid axon were labeled with I2~1 by using an enzymatic radio-iodination procedure in combination with the intracellular perfusion technique. This study demonstrated that a protein with a molecular weight equal to about 12,000 daltons was associated with the internal membrane surface, and the ability of this protein to be iodinated was selectively reduced by potassium depolarization of the axon.…”

Section: Introductionmentioning

confidence: 99%

Release of proteins from the inner surface of squid axon membrane labeled with tritiated N-ethylmaleimide.

Inoue¹,

Pant²,

Tasaki³

et al. 1976

The Journal of General Physiology

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Proteins in the inner surface of the squid axon membrane were labeled by intracellular perfusion of [aH]N-ethylmaleimide (NEM), which forms covalent bonds with free sulfhydryl groups. The excitability of the axon was unaffected by the [aH]NEM perfusion. After washout of the unbound label, the perfusate was monitored for the release of labeled proteins. Labeled proteins were released from the inner membrane surface by potassium depolarization of the axon only in the presence of external calcium ions. Replacement of the fluoride ion in the perfusion medium by various anions also caused labeled protein release. The order of effectiveness was SCN->> Br-> C1-> F-. The extent of labeled protein release by the various anions was correlated with their effects on axonal excitability. The significance of these results is discussed.

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“…Electron microscopically, Metuzals and Tasaki (1978) showed that a three-dimensional network of interwoven filaments consisting partly of an actin-like protein is firmly attached to the axolemma and might have a role in some aspect of excitability. Upon analyzing axonal proteins in perfusate with SDS-polyacrylamide gel electrophoresis, Gainer et al (1974), Inoue et aL (1976), and Takenaka et al (1976) concluded that a 12,000-dalton protein was released after repetitive electrical stimulation of the axon or by potassium depolarization. However, quite recently, Pant et al (1978) concluded that an appreciable amount of a 45,000-dalton protein, in addition to the 12,000 daltons, presented in the perfusate from the stimulated axon or the axon exhibiting long-lasting action potential, while a 68,000-dalton protein dominated in the perfusate from the depolarized axon.…”

mentioning

confidence: 98%

Microtubules inside the plasma membrane of squid giant axons and their possible physiological function

Matsumoto¹,

Sakai²

1979

J. Membrain Biol.

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The effects of application of the microtubule-disassembling reagents to squid giant axons upon resting potential, the height of the propagated action potential, and the threshold to evoke action potential were studied using colchicine, podophyllotoxin, vinblastine, griseofulvin, sulfhydryl reagents including NEM, diamide, DTNB and PCMB, and Ca2+ ions. At the same time, the effects of concentrations of K halides and K glutamate on the above physiological properties were studied in comparison with in vitro characteristics of microtubule assembly from purified axoplasmic tubulin. It was found that there was good correlation between conditions supporting maintenance of membrane excitability and microtubule assembly. The experiments suggest that associated with the internal surface of the plasma membrane there are microtubules which regulate in part both the resting and action potentials.

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Depolarization-induced change in the enzymatic radio-iodination of a protein on the internal surface of the squid giant axon membrane

Cited by 17 publications

References 9 publications

Cell-to-cell transfer of glial proteins to the squid giant axon: The glia- neuron protein transfer hypothesis

Cell-to-cell transfer of glial proteins to the squid giant axon: The glia- neuron protein transfer hypothesis

Release of proteins from the inner surface of squid axon membrane labeled with tritiated N-ethylmaleimide.

Microtubules inside the plasma membrane of squid giant axons and their possible physiological function

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