We have identified a nu
mber of type I and type II keratins in the zebrafish Danio rerio by two-di
mensional polyacryla
mide gel electrophoresis, co
mple
mentary keratin blot-binding assay and i
mmunoblotting. These keratins range fro
m 56 kDa to 46 kDa in
molecular
mass and fro
m pH 6.6 to pH 5.2 in isoelectric point. Type II zebrafish keratins exhibit significantly higher
molecular
masses (56-52 kDa) co
mpared with the type I keratins (50-48 kDa), but the isoelectric points show no significant difference between the two keratin subclasses (type II: pH 6.0-5.5; type I: pH 6.1-5.2). According to their occurrence in various zebrafish tissues, the identified keratins can be classified into "E" (epider
mal) and "S" (si
mple epithelial) proteins. A panel of
monoclonal anti-keratin antibodies has been used for i
mmunoblotting of zebrafish cytoskeletal preparations and i
mmunofluorescence
microscopy of frozen tissue sections. These antibodies have revealed differential cytoplas
mic expression of keratins; this not only includes epithelia, but also a variety of
mesenchy
mally derived cells and tissues. Thus, previously detected funda
mental differences in keratin expression patterns between higher vertebrates and a sal
monid, the rainbow trout Oncorhynchus
mykiss, also apply between vertebrates and the zebrafish, a cyprinid. However, in spite of notable si
milarities, trout and zebrafish keratins differ fro
m each other in
many details. The present data provide a fir
m basis fro
m which the application of keratins as cell differentiation
markers in the well-established genetic
model organis
m, the zebrafish, can be developed.
相似文献