Bean homologs of the mammalian glucose-regulated proteins: induction by tunicamycin and interaction with newly synthesized seed storage proteins in the endoplasmic reticulum

Plant J. 1992 Jul;2(4):443-55. doi: 10.1111/j.1365-313x.1992.00443.x.

Abstract

Treatment of developing bean cotyledons with the inhibitor of N-glycosylation tunicamycin enhanced the synthesis of at least two polypeptides with molecular mass 78 kDa and 97 kDa. Pulse-chase experiments and subcellular fractionation indicated that these are endoplasmic reticulum (ER) residents. The 78 kDa protein is a major component of the ER protein fraction and, by N-terminal sequencing, was identified as a bean homolog of the mammalian 78 kDa glucose-regulated protein (GRP78). This is a molecular chaperone that is probably involved in the folding and oligomerization of several animal and yeast proteins in the ER. When newly synthesized storage glycoproteins phaseolin, phytohemagglutinin or alpha-amylase inhibitor were immunoprecipitated from an ER preparation of tunicamycin-treated tissue, the GRP78 homolog was always co-precipitated. Bound GRP78 homolog could be released by ATP treatment. These results suggest that, at least when glycosylation is inhibited, this protein plays a role in the early stages of the synthesis of vacuolar storage proteins.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Carrier Proteins / biosynthesis*
  • Carrier Proteins / isolation & purification
  • Carrier Proteins / metabolism
  • Endoplasmic Reticulum / metabolism
  • Fabaceae / drug effects
  • Fabaceae / metabolism*
  • Heat-Shock Proteins*
  • Mammals
  • Mice
  • Molecular Chaperones*
  • Molecular Sequence Data
  • Organelles / metabolism
  • Plant Proteins / biosynthesis*
  • Plant Proteins / isolation & purification
  • Plant Proteins / metabolism
  • Plants, Medicinal*
  • Seeds / metabolism*
  • Sequence Homology, Amino Acid
  • Tunicamycin / pharmacology*

Substances

  • Carrier Proteins
  • Heat-Shock Proteins
  • Molecular Chaperones
  • Plant Proteins
  • Tunicamycin
  • molecular chaperone GRP78

Associated data

  • GENBANK/P80089