clathrinpositive

Clathrinpositive is an informal descriptor used in cell biology to denote cells, vesicles, or compartments that display clathrin on their surface or coat, as detected by immunostaining or fluorescent tagging. Clathrin is a cytosolic protein that self-assembles into a polyhedral lattice, forming clathrin-coated pits and vesicles involved in clathrin-mediated endocytosis and in trafficking from the trans-Golgi network to endosomes and lysosomes.

In the plasma membrane, adaptor proteins such as AP-2 recruit clathrin to form coated pits that invaginate and pinch off as clathrin-coated vesicles; similar coats participate in post-Golgi trafficking with adaptors such as AP-1. Clathrin-positive labeling is commonly observed in fluorescence or electron microscopy when studying endocytosis and vesicular trafficking.

Researchers may co-stain for clathrin and markers like the transferrin receptor to identify clathrin-mediated uptake, or with EEA1 to mark early endosomes, helping infer the route of internalized cargo. Interpretations based on clathrin positivity should consider that the presence of clathrin indicates structural components of coated vesicles or pits, but does not by itself confirm ongoing functional trafficking, given clathrin-independent pathways can contribute to endocytosis and coats can persist after vesicle uncoating.

Limitations include fixation and antibody specificity, image resolution, and context. In some studies, clathrin positivity helps characterize endocytic activity, cell states, or responses to stimuli, but it should be interpreted alongside other markers to determine the precise trafficking pathway.