Identification of two structurally related proteins involved in proteolytic processing of precursors targeted to the chloroplast

EMBO J. 1992 Dec;11(12):4401-9.

Abstract

Two proteins of 145 and 143 kDa were identified in pea which co-purify with a chloroplast processing activity that cleaves the precursor for the major light-harvesting chlorophyll binding protein (preLHCP). Antiserum generated against the 145/143 kDa doublet recognizes only these two polypeptides in a chloroplast soluble extract. In immunodepletion experiments the antiserum removed the doublet, and there was a concomitant loss of cleavage of preLHCP as well as of precursors for the small subunit of Rubisco and the acyl carrier protein. The 145 and 143 kDa proteins co-eluted in parallel with the peak of processing activity during all fractionation procedures, but they were not detectable as a homo- or heterodimeric complex. The 145 and 143 kDa proteins were used separately to affinity purify immunoglobulins; each preparation recognized both polypeptides, indicating that they are antigenically related. Wheat chloroplasts contain a soluble species similar in size to the 145/143 kDa doublet.

Publication types

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

MeSH terms

  • Biological Transport
  • Blotting, Western
  • Centrifugation, Density Gradient
  • Chloroplasts / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes
  • Fabaceae / chemistry
  • Hydrolysis
  • Molecular Weight
  • Plant Proteins / chemistry
  • Plant Proteins / immunology
  • Plant Proteins / metabolism*
  • Plants, Medicinal
  • Protein Conformation
  • Protein Precursors / metabolism*
  • Protein Processing, Post-Translational*
  • Substrate Specificity
  • Triticum / chemistry

Substances

  • Epitopes
  • Plant Proteins
  • Protein Precursors