Identification of cDNA for rat homologues of human major basic protein and eosinophil cationic protein

We have determined the complete nucleotide sequence for cDNA of rat homologues of human eosinophil major basic protein (MBP) and eosinophil cationic protein (ECP) using the rapid amplification of cDNA ends (RACE) procedure. Nucleotide sequence of cDNA of rat MBP revealed that mRNA of rat MBP encodes a protein containing 227 amino acids which has three functional domains; namely, the signal peptide, the acidic peptide that contains numerous acidic amino acids and the mature MBP, as in human, guinea pig and mouse MBP. In addition, cDNA of a rat homologue of human ECP was also cloned. The deduced amino acid sequence revealed that this gene encodes a putative protein with a molecular weight of 15.5 kD which has ribonuclease activity. The homology of amino acid sequence between the rat homologue and the murine eosinophil-associated ribonucleases (EARs) was high (65%). Therefore, we named this rat homologue 'rat EAR-1'.