CLONING AND EXPRESSION OF ODORANT BINDING-PROTEINS IA AND IB FROM MOUSE NASAL TISSUE

We had previously reported the purification and partial characterisati on of four distinct odorant-binding proteins from male mouse nasal epi thelium. One of these, named OBP-I appeared to be a heterodimer, whose subunits, Ia and Ib showed significant similarity in their N-terminal amino acid sequences with hamster aphrodisin. In this paper, we repor t the complete amino acid sequences of these two polypeptide chains, a s deduced from nucleotide sequences of their relative cDNA. These data confirm the high similarity of both proteins with hamster aphrodisin. A comparison with the sequences of other known OBPs indicate that the y are more closely related to members of class I, including bovine OBP , rat OBP-I and pig OBP-I. A putative odorant-binding site is indicate d by the presence of amino acid residues conserved with respect to the bovine protein, whose three-dimensional structure has been recently r esolved. In-situ hybridisation has revealed identical expression patte rns for the two proteins, further supporting the heterodimeric structu re of these proteins in the nasal mucus. (C) 1998 Elsevier Science B.V . All rights reserved.