Nov 1, 1977

Properties of a P70 proteolytic factor of murine leukemia viruses

Y Yoshinaka, R B Luftig


Murine leukemia viruses, such as Rauscher leukemia virus (RLV), contain a proteolytic factor which becomes activated after detergent treatment of the virus. This factor specifically cleaves P70, the gag precursor polyprotein which is enriched for in preparations of immature virus core subparticles. The factor has been partially purified on Sephadex G-75 columns. It has a molecular weight of 10,000-12,000 daltons but does not coincide in elution position with the major peaks of the viral polypeptides p10 or p12. Under optimal conditions, that is 2% NP-40 (v/v), 10 mM DTT, (pH 7.2) and incubation for 16 hr at 22 degrees C, cleavage of labeled P70 occurs and increasing amounts of the four gag polypeptides p30, p15, p12 and p10 are obtained. The P70 cleavage activity is blocked by TLCK, TAME, CBZ-lysine and other lysyl-containing protease inhibitors. Further, the CBZ-lysine inhibition is reversible, while an inhibition by phenyl-methylsulfonyl fluoride (PMSF) is irreversible. These inhibition studies suggest that a similarity exists between the P70 proteolytic factor and some serine proteases, such as trypsin. The cleavage pattern of P70-rich immature cores treated with trypsin or chymotrypsin is different from that obtained with t...Continue Reading

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Mentioned in this Paper

Protease Inhibitors [MoA]
Rauscher Virus
Fluoride Measurement
Virus core
Murine leukemia virus
Viral Proteins
Antigenic Specificity

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