Studies of the biological activity of insulin, cyclic nucleotides and concanavalin A in the isolated fat cell.

The insulin or proinsulin response of the isolated rat adipocyte was destroyed by preincubation with trypsin. After 120 minutes, biological responsiveness partially regenerated. Similarly, the biological responsiveness of the isolated fat cell to non-suppressible insulin-like activity (NSILA) was only partially destroyed following trypsin digestion, and did not regenerate. In contrast to the above, cyclic AMP or dibutyryl cyclic AMP effects were unaltered by trypsin or neuraminidase digestion.