<p>Certain globular proteins from different functional families contain non-globular alpha+beta subunits. These proteins do not form a true superfamily, but share a similar topology in their non-globular subunits. Proteins that display this structure include phycoerythrin 545 alpha subunits (<db_xref db="INTERPRO" dbkey="IPR004228"/>), which are light-harvesting biliproteins found in cryptomonads [<cite idref="PUB00014305"/>], the chaperone-binding domain of the virulence effector SptP from <taxon tax_id="602">Salmonella typhimurium</taxon>, which acts to modulate host cellular responses [<cite idref="PUB00014306"/>], and the ubiquinol-cytochrome c reductase 8kDa protein (<db_xref db="EC" dbkey="1.10.2.2"/>), an integral membrane protein complex essential to cellular respiration [<cite idref="PUB00014307"/>].</p>