Molecular cloning and tissue distribution of ferritin in Pacific white shrimp (Litopenaeus vannamei)

Ferritin, a cytosolic iron storage protein composed of 24 subunits of heavy chain and light chain, is an intracellular protein primarily involved in iron metabolism. It can sequester up to 4500 ferric ions in its inner core to protect cells against toxicity of iron. Ferritin is known to play important roles in detoxification and is also involved in immunity processes. In this study, a full-length ferritin cDNA was cloned from the haemocyte of the Pacific white shrimp, Litopenaeus vannamei: it comprises 1249 bp, including 132 bp in the 5'-untranslated region, 510 bp in the open reading frame which encodes 170 amino acid residues, and 607 bp in the 3'-untranslated region. Alignments of the deduced amino acid sequence showed that the Pacific white shrimp ferritin shares 74%, 69%, 62%, 67%, 50% and 48% identity with crayfish, tick, brine shrimp, oyster, human and rat, respectively. The tissue-specific expression pattern was examined by reverse transcription polymerase chain reaction and real-time quantitative PCR. The ferritin mRNA is expressed in various tissues of the shrimp in the order of haemocyte, midgut gland, brain ganglion, gill, hepatopancreas, abdominal ganglion, eyestalk, muscle, thoracic ganglion, and heart.