Rat Liver Asialoglycoprotein Receptor Lacks a Cleavable NH2-terminal Signal Sequence

Two cDNA clones encoding the predominant form of the asialoglycoprotein receptor from rat liver (the major rat hepatic lectin; RHL-1) were identified by screening a rat liver cDNA library with a mixed oligonucleotide probe 35 nucleotides long. One clone was a nearly full-length copy of the mRNA for RHL-1, while the other was shortened at both ends. The sequences of these clones demonstrate that this transmembrane receptor is not synthesized with an NH2-terminal signal sequence. The only proteolytic processing occurring in the biosynthesis of RHL-1 is the removal of the NH2-terminal initiator methionine residue. Insertion of RHL-1 into the membrane is postulated to occur by the recognition of the internal transmembrane region as a signal sequence.