p46

P46 is a designation used in biology to denote a protein with an approximate molecular weight of 46 kilodaltons. Because it is a mass-based label rather than a fixed gene name, the meaning of “p46” varies by context and species. In practice, the term is most often encountered as an informal name for a specific protein isoform or a member of a protein family that includes other 46-kDa variants.

In humans, the best-known example is the p46Shc isoform of the SHC1 adaptor protein. SHC1 encodes several SH2-domain–containing adaptor proteins that relay signals from receptor tyrosine kinases to downstream pathways such as Ras–MAPK. The p46Shc isoform is produced by alternative splicing and functions as part of the Shc1 family alongside the better-characterized p52Shc and p66Shc isoforms. p46Shc participates in signaling initiated by growth factor receptors, helping to recruit Grb2 and activating downstream Ras signaling. Its activity is regulated by phosphorylation, which influences interactions and subcellular localization, and it can impact cellular processes such as proliferation and differentiation. Aberrant expression or signaling involving Shc1 isoforms has been examined in various cancers and developmental contexts.

Other uses of the label p46 exist in different biological contexts, reflecting the general practice of naming proteins by their approximate molecular weight. Because “p46” is not a unique identifier, precise identification typically requires accompanying details such as the full protein name, gene symbol, or sequence information.