[Structural organization of rat ceruloplasmin gene]

Distribution of ceruloplasmin-coding sequences among fragments of rat nuclear DNA obtained after complete cleavage with seven restriction endonucleases was studied using highly specific complementary DNA probes. Three different procedures were used for the synthesis of cDNAs, whose relative advantages and disadvantages are discussed in this work. The number of restriction fragments carrying ceruloplasmin gene sequences varied from two to five depending on the enzyme used. The total molecular weight of these fragments was several times higher than the minimal length of ceruloplasmin structural gene deduced from the molecular size of mRNA. The restriction endonuclease cleavage of the partial double-stranded transcript of ceruloplasmin mRNA coding for about 60% of its length from the 3'-end has shown that distribution of restriction endonuclease cleavage sites on the dsDNA differs in the position of cleavage sites on the ceruloplasmin gene in cellular DNA. Hybridization of cDNA with total cellular DNA allows to determine 1.3-1.4 copies of ceruloplasmin gene in the rat haploid genome. Proceeding from the data obtained it may be stated that the rat ceruloplasmin gene is constructed of several structural gene segments cut by introns.