ENDOGENOUS CELLULAR REVERSE-TRANSCRIPTASE FROM RAT-BRAIN - COMPARATIVE-ANALYSIS OF THE AUTHENTIC ENZYME AND A RECOMBINANT REVERSE-TRANSCRIPTASE CODED BY A MOBILE GENOME ELEMENT OF THE LINE FAMILY

An endogenous RNA-dependent DNA polymerase (reverse transcriptase) ear lier identified in rat brain (Ivanov, V. A., Pakhotin, P. I., Bobkova, N. V., and Ilyin, Yu. V. (1992) Dokl. Ross. Akad. Nauk, 323, 173-177) has been purified. This enzyme and a recombinant reverse transcriptas e coded by the mobile genome element jockey expressed earlier in a het erologous cell system (Ivanov, V. A., Melnikov, A. A., Siunov, A. V., Fodor, I. I., and Ilyin, Yu. V. (1991) EMBO J., 10, 2489-2495) have be en comparatively analyzed. Like retroviral RNA-dependent DNA polymeras es, the enzymes prefer polyribonucleotides and can use poly(rC(III)) a s template. Also, they are inhibited by SH-reagents and require bivale nt cations (Mg2+ or Mn2+) and detergent and/or KCL as ionic strength c arrier. But the enzymes differ drastically from the retroviral reverse transcriptases in a number of catalytic properties (low optima of con centration of requisite cations and ionic strength, strong preference for Mn, high efficiency in using poly(rC(III)), lack of associated RNa seH activity) and are very similar to each other with regards to these properties. presumably, the endogenous reverse transcriptase from rat brain is a product of expression of a mobile genome element of the LI NE family.