Blood-borne type non-A, non-B (NANB) hepatitisassociated microtubular aggregates protein was isolated and partially sequenced. The microtubular aggregates were isolated from the hepatocytes of NANBinfected chimpanzees and were found to have a buoyant density in sucrose solution of 1.21 to 1-23 g/ml. A single protein, recognized by our anti-microtubular aggregates monoclonal antibodies, was found to have an M~ of 44 000 (p44). This p44 protein was not found in uninfected chimpanzees. We determined a partial amino acid sequence for p44, and showed that it has no homology to any known proteins.

Hepatocyte growth factor (HGF) promotes proliferation of cultured hepatocytes by its interaction with cell surface receptors. In this paper, we examined the metabolic fate of HGF using hepatocytes. Kinetic analysis using ["'I]HGF showed that 40% of surface-bound HGF was rapidly internalized in hepatocytes within 30 min at 37°C. Under these conditions, the amount of HGF-bound c-Met, the high-affinity receptor, decreased from the cell surface. Furthermore, the internalized HGF was degraded and released from the cells. These results indicate that cell surface-bound HGF is internalized and degraded by the receptors, including c-Met, on hepatocytes.

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