| Summary: | 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.
|
|---|
