charged amino acids which can be of importance for the binding of cations to oct1 various rat tissues and some cell lines were analyzed for the localisation of oct1 transport protein specific mrna using so called northern blots for this purpose the total rna was isolated by the the guanidinium phenol chloroform method and the mrna was purified by means of oligo dt cellulose chromatography the mrna was fractionated by formaldehyde agarose gel electrophoresis transferred to a hybond n membrane amersham and then hybridized for this 5 u03bcg of mrna from the rat cells and from the cell line 293 and 1 5 u03bcg of mrna from the cell lines caki 1 and llc pki1 were loaded onto the formaldehyde agarose gel the hybridization was carried out using a 32 p labeled cdna fragment of the novel dna sequence from plasmid poct1 nucleotides 285 to 1196 were used the hybridization was carried out in hybridization solution 50 formamide 5 u00d7 sspe 5 u00d7 denhardt 39 s solution 0 5 sds and 20 u03bcg of salmon sperm dna at 42 u00b0 c for 18 hours the membrane was washed in several steps to a final stringency of 0 25 u00d7 sspe 0 1 sds at 60 u00b0 c to display the results for cell line llc pk1 the film was exposed for 24 hours and the film was exposed for 6 hours for the other tracks an rna standard 0 14.