[mRNA for the plasminogen activator of the urokinase type: translation in oocytes of Xenopus laevis].

Poly(A)+-RNA from human kidney and human embryonal lung fibroblasts fractionated by sucrose gradient centrifugation was translated in Xenopus oocytes. Assay for plasminogen-dependent fibrinolytic activity detected synthesis of secreted plasminogen activator and revealed the active fraction of poly(A)+-RNA with a sedimentation coefficient of approximately 23S. Translation products of the active fraction were immunoadsorbed by antiurokinase monoclonal antibodies immobilized on sepharose. Gel electrophoretic analysis of the protein products showed that the 23S fraction of poly(A)+-RNA from human kidney contains mRNA for single-chain urokinase-type plasminogen activator with apparent molecular weight of approximately 50 kDa.