pk1p

Pk1p, also written PK1P, is a prototypical eukaryotic serine/threonine protein kinase used in educational contexts to illustrate common features of signaling kinases. It is not tied to a specific, experimentally validated gene in major databases, but serves as a generic reference in textbooks and tutorials.

Structure: As with canonical protein kinases, pk1p is depicted as containing a bilobal catalytic core. The smaller N-terminal lobe provides ATP-binding capacity, while the larger C-terminal lobe binds substrate peptides. Conserved motifs include a glycine-rich loop (GxGxxG) at the ATP-binding site, the VAIK motif in subdomain II, and the catalytic HRD motif with the DFG motif in the activation loop. Regulatory regions vary by illustration but often include extensions that govern localization, protein interactions, and autoinhibition or activation.

Function and regulation: Pk1p is described as phosphorylating serine or threonine residues on substrate proteins, thereby modulating signaling pathways that control growth, differentiation, cytoskeletal organization, or stress responses. In example pathways, activity is regulated by phosphorylation of the activation loop, interaction with regulatory subunits, and upstream kinases or phosphatases.

Localization and interactions: In representations, pk1p localizes to the cytosol or membrane-proximal sites, with potential nuclear access. It commonly interacts with scaffolds that organize signaling complexes and with substrates containing docking motifs.

Nomenclature and scope: Because pk1p is an archetype, it is used across educational materials rather than as a defined gene. Real-world kinases with similar architecture exist and are annotated in species-specific databases; pk1p serves as a model rather than a canonical entry.