p33

p33 is a designation used in biology to denote proteins that are typically around 33 kilodaltons in size, and it is also the specific name given to a viral replication protein in certain plant viruses. Because “p33” is a generic label based on molecular weight, it can refer to different proteins in different organisms, and there is no single universal entity named p33.

In virology, p33 has a well-documented role in the tombusviruses, a group within the family Tombusviridae. In these viruses, p33 is encoded by the first open reading frame of the viral genome, while a larger replication protein, p92, is produced by read-through of the p33 stop codon. The two proteins, p33 and p92, collaborate to form the viral RNA replication complex on intracellular membranes, enabling replication of the viral genome. The p33 protein is considered essential for replication alongside p92, and the replication efficiency and host interactions can be influenced by both components.

Outside of this context, “p33” serves as a shorthand for other 33-kilodalton proteins found in various species, reflecting the common practice of naming proteins by approximate molecular weight. Because many different proteins can fall near 33 kDa, the exact identity and function of a given p33 depend entirely on the organism and the gene in question. Consequently, when encountering the term p33, it is important to rely on contextual information to determine whether it refers to a viral replication protein, a host protein, or another 33-kDa protein.