EMBL accession no. X13722 A 4.7 kb cDNA clone (ArLDL2-1a) coding for the rat low density lipoprotein (LDL) receptor was isolated from a Xgt-11 rat liver cDNA library (1,2). The DNA sequence of the entire coding region and portions of the 5' and 3' untranslated region is shown in Figure 1. The open reading frame coded for an 879 amino acid polypeptide with a theoretical molecular weight of 96,632, which is larger than the size of the human (3) and rabbit (4) LDL receptors. A signal sequence of 21 amino acids was also present in both the rat (Fig. 1) and human (3) receptors.