Rhizostomins

Rhizostomins are proteins that are part of a pigment family only found in jellyfish in the order Rhizostomeae.^[1] These proteins are composed of a Kringle domain inserted within a cysteine-rich Frizzled domain,^[1] first identified in 2004 as the blue pigment in the barrel jellyfish Rhizostoma pulmo.^[2] It also appears in rhizostome jellyfish that do not appear blue, such as in Nemopilema nomurai, which typically presents red-brown coloration. It has been hypothesized that pigments in this family act as a sunscreen, protecting from harmful ultraviolet radiation.^[1][3] Natural blue pigments, such as some of the rhizostomins, are rare and there is a growing need for industrial purposes.^[4]