Molecular analysis of an auxin binding protein gene located on chromosome 4 of Arabidopsis.
We have isolated a cDNA clone from Arabidopsis, At-ERabp1, for the Arabidopsis auxin binding protein located in the lumen of the endoplasmic reticulum (ER). This cDNA clone codes for a protein related to the major auxin binding protein from maize, Zm-ERabp1. A single open reading frame, 594 bases in length, predicts a protein of 198 amino acid residues and a molecular mass of 22,044 D. The primary amino acid sequence contains an N-terminal hydrophobic signal sequence of 33 amino acids. We demonstrated by in vitro studies that the At-ERabp1 protein is translocated into ER-derived microsomes. The protein was processed, and the cleavage site for the N-terminal signal peptide was determined by radiosequencing. The mature protein is composed of 165 amino acid residues, with a molecular mass of 18,641 D. The At-ERabp1 protein contains potential N-glycosylation sites (Asn46-Ile-Ser and Asn130-Ser-Thr). In vitro transport studies demonstrated cotranslational glycosylation. Retention within the lumen of the ER correlates with an additional signal located at the C terminus and represented by the amino acids Lys196-Asp-Glu-Leu, well known to be essential for active retrieval of proteins into the lumen of the ER. DNA gel blot analysis of genomic DNA revealed single hybridizing bands, suggesting that only a single At-ERabp1 gene is present in the Arabidopsis genome. Restriction fragment length polymorphism mapping indeed revealed a single locus mapping to chromosome 4.
Palme
K
K
Max-Planck-Institut für Züchtungsforschung, Köln, Germany.
Hesse
T
T
Campos
N
N
Garbers
C
C
Yanofsky
M F
MF
Schell
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid
D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C046131:auxin receptor, plant; D004247:DNA