Passage through vertebrate gap junctions of 17/18kDa molecules is primarily dependent upon molecular configuration.
In fish, amphibians and mammals, gap junctions of some cells allow passage of elongate molecules as large as 18kDa, while excluding smaller, less elongate molecules. Fluorescently labeled Calmodulin (17kDa) and fluorescently labeled Troponin-C (18kDa), when microinjected into oocytes of Danio rerio, Xenopus laevis or Mus domestica, were able to transit the gap junctions between these oocytes and the granulosa cells which surrounded them. Co-microinjected with these Ca(2+)-binding proteins, Texas-red-labeled dextran (10kDa) remained in the microinjected cell. Osteocalcin (6kDa), also a Ca(2+)-binding protein, but with a wide "V" shape proved unable to transit these gap junctions. Calmodulin, but not Troponin-C, was able to transit gap junctions of gonadotropin treated WB cells in culture. We show evidence that molecules as large as 18kDa can pass through some vertebrate gap junctions, both homologous and heterologous, and that it is primarily molecular configuration which governs gap junctional permeability.
Cieniewicz
A M
AM
Department of Biology, West Chester University, West Chester, PA 19383, USA.
Woodruff
R I
RI
D000818:Animals; D002147:Calmodulin / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology; D018929:Cell Culture Techniques; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000502:physiology; D002478:Cells, Cultured; D003911:Dextrans / Q000378:metabolism; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism* / Q000648:ultrastructure; D006107:Granulosa Cells / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D051379:Mice; D008845:Microinjections; D008968:Molecular Conformation; D008970:Molecular Weight; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D015675:Osteocalcin / Q000378:metabolism; D019209:Troponin C / Q000378:metabolism; D014966:Xanthenes / Q000378:metabolism; D014982:Xenopus laevis; D015027:Zebrafish
D002147:Calmodulin; D003911:Dextrans; D005456:Fluorescent Dyes; D019209:Troponin C; D014966:Xanthenes; D015675:Osteocalcin; C034657:Texas red