Hemolin is an immunoglobulin-like protein exclusively found in Lepidoptera (moths and butterflies). It was first discovered in immune-challenged pupae of Hyalophora cecropia [1] and Manduca sexta . [2]
Hemolin has a horseshoe crystal structure [3] with four domains and resembles the developmental protein neuroglian.
Hemolin increases 18-fold up to 7 mg/ml following injection of bacteria in H. cecropia. Induction of Hemolin in moths after bacterial injection have been shown in several species including Antheraea pernyi , [4] Bombyx mori , Helicoverpa zea , [5] Heliothis virescens , [6] Hyphantria cunea , [7] and Samia cynthia . [8]
Hemolin has also been suggested to participate in the immune response to virus infection [9] and shown to bind to virus particles. [10] It is expressed in response to dsRNA in a dose-dependent manner. [11] Galleria melonella responds to caffeine intake by increased Hemolin protein expression. [12]
Hemolin is thought to be a gene duplication of the developmental protein neuroglian, [13] but has lost two of the protein domains that neuroglian contains. In the potential function as a developmental protein, Hemolin has been shown to increase close to pupation in Manduca sexta , [14] and is induced during diapause and by 20-Hydroxyecdysone in Lymantria dispar . [15] RNAi of Hemolin causes malformation in H. cecropia. [16]