The cyclophilin homolog ninaA is required in the secretory pathway

Cell. 1991 Oct 18;67(2):255-63. doi: 10.1016/0092-8674(91)90177-z.

Abstract

In Drosophila, the major rhodopsin Rh1 is synthesized in endoplasmic reticulum (ER)-bound ribosomes of the R1-R6 photoreceptor cells and is then transported to the rhabdomeres where it functions in phototransduction. Mutations in the cyclophilin homolog ninaA lead to a 90% reduction in Rh1 opsin. Cyclophilins have been shown to be peptidyl-prolyl cis-trans isomerases and have been implicated in catalyzing protein folding. We now show that mutations in the ninaA gene severely inhibit opsin transport from the ER, leading to dramatic accumulations of ER cisternae in the photoreceptor cells. These results demonstrate that ninaA functions in the ER. Interestingly, ninaA and Rh1 also colocalize to secretory vesicles, suggesting that Rh1 may require ninaA as it travels through the distal compartments of the secretory pathway. These results are discussed in relation to the possible role of cyclophilins in protein folding and intracellular protein trafficking.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Isomerases / genetics
  • Amino Acid Isomerases / metabolism*
  • Amino Acid Isomerases / physiology
  • Animals
  • Animals, Genetically Modified / genetics
  • Blotting, Western
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Carrier Proteins / physiology
  • Drosophila Proteins*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / metabolism*
  • Electric Conductivity
  • Endoplasmic Reticulum / metabolism*
  • Immunohistochemistry
  • Insect Hormones / genetics
  • Insect Hormones / metabolism*
  • Insect Hormones / physiology
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Membrane Proteins / physiology
  • Microscopy, Immunoelectron
  • Molecular Chaperones*
  • Mutation / genetics
  • Peptidylprolyl Isomerase
  • Photic Stimulation
  • Photoreceptor Cells / metabolism
  • Protein Conformation
  • Rhodopsin / genetics
  • Rhodopsin / metabolism*

Substances

  • Carrier Proteins
  • Drosophila Proteins
  • Insect Hormones
  • Membrane Glycoproteins
  • Membrane Proteins
  • Molecular Chaperones
  • ninaA protein, Drosophila
  • Rhodopsin
  • Amino Acid Isomerases
  • Peptidylprolyl Isomerase