title: Isolation and characterization of the retinoblastoma protein from fish.
abstract: The retinoblastoma (Rb) gene represents the first tumor suppressor gene characterized. The encoded protein, pRb, plays a crucial role in cell cycle control, preventing malignant cell proliferation. Recently, homologues of the Rb gene have been isolated in fish and the pocket domain, which is central to Rb function, was conserved. In our studies, using coelocanth (Latimeria chalumnae), rainbow trout (Oncorhynchus mykiss), medaka (Oryzias latipes) and English sole (Parophrys vetulus), we have developed a simple protocol for the isolation of the Rb tumor suppressor protein and determined its' tissue and cellular localization. Fish Rb proteins display apparent molecular weights in the range of 100-110 kDa, similar to the human pRb. The protein was detected in all tissues examined, consistent with the proteins' universal role in cellular signalling. An interesting pattern of immunoreactive bands was detected in each of the cells' two main compartments, suggesting differential proteolysis. Immuno-analysis of the pRb in trout liver tumor material revealed an additional Rb reactive product that was absent in normal liver cell extracts.
authors.affiliation: Department of Biology and Division of Comparative Medicine, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Rotchell
authors.forename: B
authors.initials: B
authors.lastname: Scoggins
authors.forename: J B
authors.initials: JB
authors.lastname: Blair
authors.forename: G K
authors.initials: GK
authors.lastname: Ostrander
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D029941:Fish Proteins / Q000737:chemistry / Q000302:isolation & purification*; D005399:Fishes; D022781:Hepatocytes / Q000737:chemistry; D006801:Humans; D008970:Molecular Weight; D009990:Oryzias; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000302:isolation & purification*; D014337:Trout
chemical_list: D029941:Fish Proteins; D016160:Retinoblastoma Protein