Retroviral aspartyl proteases or retropepsins are single domain aspartyl proteases from

retroviruses A retrovirus is a type of virus that inserts a DNA copy of its RNA genome into the DNA of a host cell that it invades, thus changing the genome of that cell. Once inside the host cell's cytoplasm, the virus uses its own reverse transcriptase e ...

, retrotransposons, and badnaviruses (plant dsDNA viruses). These proteases are generally part of a larger pol or gag polyprotein. Retroviral proteases are homologous to a single domain of the two-domain eukaryotic aspartyl proteases such as pepsins, cathepsins, and renins (; MEROPS A1). Retropepsins are members of MEROPS A2, clan AA. All known members are

endopeptidases Endopeptidase or endoproteinase are proteolytic peptidases that break peptide bonds of nonterminal amino acids (i.e. within the molecule), in contrast to exopeptidases, which break peptide bonds from end-pieces of terminal amino acids. For this re ...

. The enzyme is only active as a homodimer, as each one corresponds to half of the eukaryotic two-lobe enzyme. The two parts each contribute one catalytic aspartyl residue. Retroviral aspartyl protease is synthesised as part of the pol polyprotein that contains an aspartyl protease, a

reverse transcriptase A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genomes, ...

, RNase H and

integrase Retroviral integrase (IN) is an enzyme produced by a retrovirus (such as HIV) that integrates—forms covalent links between—its genetic information into that of the host cell it infects. Retroviral INs are not to be confused with phage int ...

. pol polyprotein undergoes specific enzymatic cleavage to yield the mature proteins. Not all retroviral aspartyl proteases generated from ''pol'' are retropepsins in the strict sense. Spumapepsin from foamy virus is divergent enough to get its own family, MEROPS A9. Many other examples are found in clan AA.

Human proteins containing this domain

DDI1 DNA-damage inducible 1 homolog 1 (S. cerevisiae) is a protein. In humans it is encoded by the DDI1 gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ' ...

;

DDI2 DDI may stand for: Companies and organizations * DD International, international TV channel in India * Development Dimensions International, a talent management company * Direct Democracy Ireland, a political party in Ireland * KDDI, formerly D ...

; ERVK6;

Human proteins containing this domain

References

See also