Carp Head Kidney Nephrosin and Embryonic Hatching Enzymes Are Members of the Astacin Family

• Main Authors: Huang,Hon-Ren, 黃宏仁
• Other Authors: Huang,Fore-Lien;Chang,Geen-Dong
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/24034845379347219826

碩士 === 國立臺灣大學 === 動物學系 === 84 === We have recently purified a metalloproteinase from the carp head kidney, an organ containing immune,hematopoietic, endocrine, and nervous tissues. Its molecular size was 25 kD, as estimated from SDS-PAGE. It was a secreted proteinase and present in the head kidney, kidney, and spleen, all of which are responsible for the immune and hematopoietic function in fish.In this study, we have cloned the cDNA encoding this metalloproteinase through antibody screening and named it nephrosin. Its transcript is present in many tissues, and is more abundant in the head kidney, kidney, spleen, and heart. It belongs to a new proteinase family,astacin family, which contains more than 20 members up to date. All of them have a signature domain, HEXXHXXGFXHEXXRXDR, and need one zinc ion as a cofactor for their activity. The first member discovered in this family is astacin, purified from the crayfish Astacus astacus. The only known members in fish are medaka, Oryzias latipes, hatching enzymes. The primary structure of nephrosin is similar to the hatching enzymes, HCE-1, HCE-2, and LCE, which are secreted to digest the egg envelope when embryos are hatching. The expression level of nephrosin in 2-days embryo is not detectable by northern and western blot in contrast to adult head kidney. In order to understand the relationship between nephrosin and hatching enzymes, we isolated two cDNA clones, CCE-1 and CCE-2, from carp embryo via RT-PCR and RACE. From the infered amino acid sequences, CCE-1 and CCE-2 are more similar to the hatching enzymes of medaka than nephrosin. Therefore, nephrosin is structurally and functionally different from hatching enzymes and is a new member of astacin family.