Regulation of catabolism of ribonuclease A microinjected into human fibroblasts.

J. F. Dice, J. M. Backer, P. Miao, L. Bourret, M. A. McElligott

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We are using ribonuclease A (RNase A) as a model protein to study how the degradative rates of proteins are regulated within cells. RNase A and several derivatives can be microinjected into confluent cultures of human fibroblasts using red cell-mediated microinjection. The half-life of RNase A is 80-100 hrs in cells maintained in the presence of serum, and the degradative rate is enhanced approximately two-fold upon serum withdrawal. The ability of fibroblasts to regulate breakdown of this protein depends on a small peptide region within the amino terminal twenty amino acids. This amino terminal peptide from RNase A can be covalently attached to unrelated proteins and will cause their catabolism to become serum responsive. The mechanism of degradation of RNase A involves lysosomal pathways both in the presence and absence of serum, and the enhanced catabolism during serum deprivation results from a two-fold increase in the rate of uptake of the protein by lysosomes. These findings suggest that autophagy, or some other process occuring in serum-deprived cells, can be highly selective.

Original languageEnglish (US)
Pages (from-to)385-394
Number of pages10
JournalProgress in clinical and biological research
StatePublished - 1985
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)


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