FATTY-ACID ACYLATED PEROXIDASE AS A MODEL FOR THE STUDY OF INTERACTIONS OF HYDROPHOBICALLY-MODIFIED PROTEINS WITH MAMMALIAN-CELLS

Artificial fatty acylation of proteins has attracted significant atten tion during the last decade as a method for modification of protein sp ecificity and efficacy of action on mammalian cells (A. V. Kabanov and V. Yu. Alakhov (1994) J. Contr. Release 28, 15-35). Horse radish pero xidase (HRP) is used in this work to study the interaction of a fatty acylated protein with various mammalian cells. The HRP is modified wit h the chloranhydride of the stearic acid in the reversed micelles of s odium bis-(2-ethylhexyl)sulfosuccinate (Aerosol OT) in octane, a conve nient protocol allowing production of protein molecules with a control led, low modification degree (A.V. Kabanov et al. (1987) Ann. N. Y. Ac ad. Sci. 501, 63-66). The influence of the hydrophobic group on the bi nding and internalization of HRP in MDCK, P3-X63-Ag8, CHO, and HepG2 c ells is examined. The major results are as follows: (i) the fatty acyl ation of a protein significantly enhances its binding to all tested ma mmalian cell lines, with a line-specific efficiency; (ii) the binding efficiency can be modified by changing growth conditions in a defined medium; (iii) along with the enhancement of protein adsorption on the plasma membrane, fatty acylation increases internalization of the prot ein during incubations at 37 degrees C; (iv) internalized protein was observed in endocytic vesicles; no evidence was obtained for a cytopla smic distribution. These results are discussed in connection with prev iously observed effects of the fatty acylated proteins on cell activit y.