Inhibition of the Degradation of the Precursor and of the Mature Beta 1 Integrin Subunit by Different Protein Synthesis Inhibitors and by ATP Depletion

A stabilization of both the precursor and the mature beta 1 integrin subunit was observed in metabolically labeled human skin fibroblasts and Molt-4 T lymphocytes upon addition of protein synthesis inhibitors or by ATP depletion. Differential effects of protein synthesis inhibitors are reported since the slow degradation of the mature beta 1 subunit was sensitive to cycloheximide but not to puromycin. We also show that the half-life of the mature subunit was not dependent on intracellular lysosomal degradation or on ubiquitination suggesting that VLA turn-over occurs at the cell surface and might involve proteins or proteases with short half-life.