A pre-organized unit composed either of adhesion molecules (mainly integrins and members of the Ig superfamily), signaling receptors and/or enzyme-enriched plasma membrane domains that compartmentalizes cellular processes. Tetraspanin-enriched microdomains might be specially suited for the regulation of avidity of adhesion receptors and the compartmentalization of enzymatic activities. [ http://www.ncbi.nlm.nih.gov/pubmed/21930792 http://www.ncbi.nlm.nih.gov/pubmed/19709882 ]