Cell and Tissue Research

, Volume 251, Issue 2, pp 257–274

The arthropod gap junction and pseudo-gap junction: Isolation and preliminary biochemical analysis

  • Robert C. Berdan
  • Norton B. Gilula
Article

DOI: 10.1007/BF00215833

Cite this article as:
Berdan, R.C. & Gilula, N.B. Cell Tissue Res. (1988) 251: 257. doi:10.1007/BF00215833

Summary

The hepatopancreas of the crayfish, Procambarus clarkii, contains an unusual abundance of gap junctions, suggesting that this tissue might provide an ideal source from which to isolate the arthropod-type of gap junction. A membrane fraction obtained by subcellular fractionation of this organ contained smooth septate junctions, zonulae adhaerentes, gap junctions and pentalaminar membrane structures (pseudo-gap junctions) as determined by electron microscopy. A further enrichment of plasma membranes and gap junctions was achieved by the use of linear sucrose gradients and extraction with 5 mM NaOH. The enrichment of gap junctions correlated with the enrichment of a 31 Kd protein band on polyacrylamide gels. Extraction with ≥20 mM NaOH or ≥0.5% (w/v) Sarkosyl NL97 resulted in the disruption and/or solubilization of gap junctions. Negative staining revealed a uniform population of 9.6 nm diameter subunits within the gap junctions with an apparent sixfold symmetry. Using antisera to the major gap junctional protein of rat liver (32 Kd) and to the lens membrane protein (MP 26), we failed to detect any homologous antigenic components in the arthropod material by immunoblotting-enriched gap junction fractions or by immunofluorescence on tissue sections. The enrichment of another membrane structure (pseudo-gap junctions), closely resembling a gap junction, correlated with the enrichment of two protein bands, 17 and 16Kd, on polyacrylamide gels. These structures appeared to have originated from intracellular myelin-like figures in phagolysosomal structures. They could be distinguished from gap junctions on the basis of their thickness, detergent-alkali insolubility, and lack of association with other plasma membrane structures, such as the septate junction. Pseudo-gap junctions may be related to a class of pentalaminar contacts among membranes involved in intracellular fusion in many eukaryotic cell types. We conclude that pseudo-gap junctions and gap junctions are different cellular structures, and that gap junctions from this arthropod tissue are uniquely different from mammalian gap junctions of rat liver in their detergentalkali solubility, equilibrium density on sucrose gradients, and protein content (antigenic properties).

Key words

Gap junction Synapse Cell junction Membrane contacts Intercellular communication Procambarus clarkii 

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • Robert C. Berdan
    • 1
  • Norton B. Gilula
    • 1
  1. 1.Department of Cell BiologyBaylor College of MedicineHoustonUSA
  2. 2.Department of Molecular BiologyResearch Institute of Scripps ClinicLa JollaUSA
  3. 3.Neuroscience Research Group and Department of Medical PhysiologyThe University of Calgary, Health Sciences CentreCalgaryCanada

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