Basolateraalisiin

Basolateral refers to the domain of the plasma membrane in polarized epithelial cells that includes the basal (facing the underlying tissue) and lateral (sides between neighboring cells) surfaces. This polarity contrasts with the apical domain, which faces the lumen or external environment. In Finnish contexts, basolateraalisiin is the illative plural form of basolateraalinen, meaning "to the basolateral (domain)."

Epithelial cells organize their plasma membrane into apical and basolateral regions through tight junctions, adherens junctions, and desmosomes. These junctions create a diffusion barrier that maintains distinct protein and lipid compositions on each surface, supporting directional transport and cell–cell adhesion.

Proteins reach the basolateral membrane via sorting pathways that involve transport through the trans-Golgi network and recycling endosomes. Basolateral signals in cargo proteins, such as tyrosine-based or dileucine motifs, are recognized by adaptor protein complexes (notably AP-1B in many vertebrate epithelia), guiding vesicles to the basolateral surface.

Basolateral localization is critical for proper function, enabling selective uptake of nutrients, ion transport, and stable adhesion to the extracellular matrix and neighboring cells. Loss of polarity or mislocalization of proteins can contribute to diseases and disrupted tissue organization.

Examples include Na+/K+ ATPase localization on the basolateral membrane of kidney tubule and intestinal epithelial cells, and basolateral sorting of transporters and receptors essential for nutrient absorption and signal transduction.

The term basolateraalisiin is used in Finnish biological texts to indicate movement toward or targeting of the basolateral domain, reflecting how global polarization concepts cross languages.