AN ALTERNATIVELY SPLICED VARIANT OF MESSENGER-RNA FOR THE HUMAN RECEPTOR FOR UROKINASE PLASMINOGEN-ACTIVATOR

Using 3'RACE (rapid amplification of cDNA ends), we have isolated a cD NA variant for the receptor for human urokinase plasminogen activator (uPAR). The deduced protein includes the amino-terminal ligand binding domain in uPAR, but lacks the carboxy-terminal membrane attachment by a glycolipid anchor. Genomic DNA analysis showed that the uPAR mRNA v ariant is generated by alternative splicing. The new variant mRNA is e xpressed in various human cell lines and tissues and both variants are up-regulated by phorbol ester in A549 cells. We propose that the alte rnatively spliced uPAR mRNA encodes a soluble uPA binding protein, the possible function of which is discussed.