Structural comparison of the precursor and the mature form of napin, the 2S storage protein in Brassica napus.
The 2S storage protein napin from Brassica napus var. L. is synthesised as a precursor protein at the endoplasmic reticulum and transported along a gradient of decreasing pH to the vacuole, where two propeptides are removed to produce mature napin. The structures of pronapin expressed in insect cells and mature napin from rape seed were characterised. Limited proteolysis with several endoproteases cleaved primarily in the propeptides, suggesting that the propeptides are exposed to the exterior of the protein. Immunological comparison in parallel with circular dichroic spectrometry, both at neutral and acid pH, indicated that the propeptides had only a minor influence on the conformation of the regions of the molecule that correspond to mature napin.
Murén
E
E
Uppsala Genetic Center, Department of Cell Research, Swedish University of Agricultural Sciences, Uppsala, Sweden. eva.muren@cellfo.slu.se
Ek
B
B
Björk
I
I
Rask
L
L
D055516:2S Albumins, Plant; D000595:Amino Acid Sequence; D000818:Animals; D001937:Brassica / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002942:Circular Dichroism; D010450:Endopeptidases; D007313:Insecta; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010940:Plant Proteins / Q000096:biosynthesis* / Q000737:chemistry*; D011487:Protein Conformation; D011498:Protein Precursors / Q000737:chemistry* / Q000378:metabolism; D012639:Seeds; D014162:Transfection
D055516:2S Albumins, Plant; D010940:Plant Proteins; D011498:Protein Precursors; C050363:napin protein, Brassica napus; D010450:Endopeptidases