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Biogenesis of surface domains in fly photoreceptor cells: Fine‐structural analysis of the plasma membrane and immunolocalization of Na + ,K + ATPase and α‐spectrin during cell differentiation
Author(s) -
Baumann Otto
Publication year - 1997
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19970616)382:4<429::aid-cne1>3.0.co;2-4
Subject(s) - biology , spectrin , microbiology and biotechnology , v atpase , biogenesis , cell , atpase , cellular differentiation , membrane , biochemistry , gene , cytoskeleton , enzyme
Electron microscopic examination of pupal and adult blowfly ( Calliphora erythrocephala ) retina provides novel details on the biogenesis of the photoreceptor surface, particularly regarding the development of the microvillar rhabdomere and associated structures, such as the submicrovillar endoplasmic reticulum. Localization of the Na + ,K + ‐ATPase on the surface of developing photoreceptors has also been examined by immunofluorescence confocal microscopy and immunogold electron microscopy. Na + ,K + ‐ATPase has a nonpolarized distribution in midpupal photoreceptors that are determined by fate but that are not yet completely differentiated. Large amounts of Na + ,K + ‐ATPase are synthesized and delivered to the cell surface throughout the second half of pupal life. At certain time points in late pupal development, specific membrane domains become cleared of Na + ,K + ‐ATPase in the photoreceptors R1–R6. However, the distribution of Na + ,K + ‐ATPase remains nonpolarized in R7/R8, even after eclosion. Because the membrane‐associated cytoskeleton plays a direct role in the establishment and maintenance of membrane domains in a variety of systems, it is of interest to study the distribution of α‐spectrin and its possible association with Na + ,K + ‐ATPase. The localization of α‐spectrin resembles the distribution pattern of Na + ,K + ‐ATPase in midpupal and adult photoreceptors. However, changes in Na + ,K + ‐ATPase localization in late pupal photoreceptors precede the redistribution of α‐spectrin by several days. Biochemical studies of cellular membranes demonstrate further that Na + ,K + ‐ATPase can be solubilized by Triton X‐100, although α‐spectrin remains in a macromolecular complex. These results indicate that the development and the maintenance of the polarized Na + ,K + ‐ATPase distribution in blowfly photoreceptors are not tightly coupled to α‐spectrin. © 1997 Wiley‐Liss Inc.