IDENTIFICATION OF MESSENGER-RNAS AND PROTEINS IN HIGHER-PLANTS USING PROBES FROM THE BAND-3 ANION TRANSPORTER OF MAMMALS

Band 3 is a well characterized ion transporter in mammalian cells, To determine if Zea mays expressed Band 3-related polypeptides, polyclona l antibodies to a 13-amino acid sequence at the carboxyl terminal end of the membrane domain of the mouse Band 3 anion transporter was used in immunoblot studies, This antiserum detected three classes of polype ptides from maize roots, The polypeptides had apparent molecular masse s of 43, 46 and 59 kDa and appeared to be integral membrane components associated with various cellular membranes including the plasma membr ane, Maize genomic DNA did not contain sequences that cross-hybridized with the mouse cDNA encoding the C-terminal membrane domain of Band 3 , However, an oligonucleotide corresponding to a portion of the 13-ami no acid sequence used for antibody preparation detected mRNAs from bot h monocotyledonous and dicotyledonous plants, The maize root and leaf mRNAs that were detected were 1.75, 1.45, and 0.88 kb in size, The lev els of the 1.75- and 1.45 kb mRNAs in maize roots did not change drama tically in response to nitrate; however, the 0.88 kb transcript levels increased in response to nitrate. Using the P-32-labelled Band 3 olig onucleotide, a partial cDNA clone (lambda B3-2758) encoding a 0.88 kb transcript was isolated. The abundance of the B3-2758 and nitrate redu ctase transcripts increased markedly in response to nitrate in an amin o acid-grown maize cell line and was well correlated with the inductio n of nitrate transport.