The Arabidopsis AXR4 gene product is involved in polar targeting of AUX1 an auxin influx carrier, to the plasma membrane (Dharmasiri et al. 2006). The AXR4 gene encodes a protein of 473 amino acids and is predicted as a Type II, integral membrane protein with a short N terminal sequence, a single transmembrane region and a large C terminal domain. The C terminus domain of AtAXR4 referred to as AtAXR4 C, was expressed as a recombinant protein in Escherichia coli and used as an antigen to generate polyclonal antibody. The antibody recognized a protein of approximately 54 kDa in the membrane fractions prepared from Arabidopsis thaliana. The availability of anti-AXR4 antibody will contribute towards elucidation of AXR4 biochemical properties and its molecular function.