IDENTIFICATION OF CDNA FOR RAT HOMOLOGS OF HUMAN MAJOR BASIC-PROTEIN AND EOSINOPHIL CATIONIC PROTEIN

We have determined the complete nucleotide sequence for cDNA of rat ho mologues of human eosinophil major basic protein (MBP) and eosinophil cationic protein (ECP) using the rapid amplification of cDNA ends (RAC E) procedure. Nucleotide sequence of cDNA of rat MBP revealed that mRN A of rat MBP encodes a protein containing 227 amino acids which has th ree functional domains; namely, the signal peptide, the acidic peptide that contains numerous acidic amino acids and the mature MBP, as in h uman, guinea pig and mouse MBP. In addition, cDNA of a rat homologue o f human ECP was also cloned. The deduced amino acid sequence revealed that this gene encodes a putative protein with a molecular weight of 1 5.5 kD which has ribonuclease activity. The homology of amino acid seq uence between the rat homologue and the murine eosinophil-associated r ibonucleases (EARs) was high (65%). Therefore, we named this rat homol ogue 'rat EAR-1'.