p0071

p0071 is an alternative name for plakophilin-3, a protein encoded by the PKP3 gene in humans. It is a member of the plakophilin family of armadillo-repeat proteins that function as desmosomal plaque components and contribute to cell–cell adhesion. The designation p0071 reflects its historical molecular weight in some early characterizations.

Function and localization

p0071 localizes predominantly to desmosomes in epithelial and some mesenchymal cells, where it helps anchor desmosomal cadherins to the intermediate filament cytoskeleton. Through its interactions with desmosomal proteins, including desmoplakin and plakoglobin, it supports desmosome assembly, stability, and the integrity of intercellular junctions. In certain contexts, plakophilins can also be found at adherens junctions and may participate in signaling pathways or shuttling to the nucleus in response to cellular cues, suggesting roles beyond purely mechanical adhesion.

Structure and interactions

p0071 contains armadillo-repeat domains that mediate a network of protein–protein interactions. It binds multiple desmosomal components such as desmoplakin, desmosomal cadherins (desmogleins and desmocollins), and other plakophilins, coordinating the linkage between the desmosomal plaque and the keratin intermediate filament network. This positioning is critical for maintaining tissue integrity under mechanical stress.

Expression and regulation

PKP3 is expressed in a wide range of epithelial tissues and may be regulated during development and in disease states. Post-translational modifications, including phosphorylation, can influence its interactions and the stability of desmosomes.

Clinical relevance

Altered expression or function of PKP3/p0071 has been explored in cancer and other diseases, with research focusing on its potential roles in cell adhesion, migration, and tumor progression. The significance of these alterations appears to be context-dependent and tissue-specific.

Discovery and naming

Historically known as p0071, the protein is now commonly referred to as plakophilin-3 (PKP3). It is one of three plakophilin family members (PKP1–PKP3) that contribute to desmosome biology in vertebrates.