TY  - JOUR
A1  - Adam, Dieter
A1  - Dimitrijevic, Nicola
A1  - Schartl, Manfred
T1  - Tumor suppression in Xiphophorus by an accidentally acquired promoter
N2  - Melanoma formation in the teleost Xiphophorus is caused by a dominant genetic locus, Tu. This locus includes the Xmrk oncogene, which encodes a receptor tyrosine kinase. Tumor induction is. suppressed in wild-type fish by a tumor suppressor locus, R. Molecular genetic analyses revealed that the Tu locus emerged by nonhomologaus recombination of the Xmrk proto-oncogene with a previously uncharacterized sequence, D. This event generated an additional copy of Xmrk with a new promoter. Suppression of the new Xmrk promoter by R in parental fish and its deregulation in hybrids explain the genetics of melanoma formation in Xiphophorus.
KW  - Physiologische Chemie
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61630
ER  - 
TY  - JOUR
A1  - Schliewen, U.
A1  - Fricke, H.
A1  - Schartl, Manfred
A1  - Epplen, Jörg T.
A1  - Paabo, S.
T1  - Which home for coelacanth?
N2  - No abstract available
KW  - Physiologische Chemie
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61606
ER  - 
TY  - JOUR
A1  - Wittbrodt, Joachim
A1  - Lammers, Reiner
A1  - Malitschek, Barbara
A1  - Ullrich, Axel
A1  - Schartl, Manfred
T1  - Xmrk receptor tyrosine kinase is activated in Xiphophorus malignant melanoma
N2  - Xmrk encodes a putative transmembrane glycoprotein of the tyrosine kinase family and is a melanoma-inducing gene in Xiphophorus. We attempted to investigate the biological function of the putative Xmrk receptor by characterizing its signalling properties. Since a potential Iigand for Xmrk has not yet been identified, it has been difficult to analyse the biochemical properlies and biological function of this cell surface protein. In an approach towards such analyses, the Xmrk extracellular domain was replaced by the closely related Iigand-binding domain sequences of the human epidennal growth factor receptor (HER) and the ligand-induced activity of the chimeric HER-Xmrk proteinwas examined. We show that the Xmrk protein is a functional receptor tyrosine kinase, is highly active in malignant melanoma and displays a constitutive autophosphorylation activity possibly due to an activating mutation in its extracellular or transmembrane domain. In the focus formation assay the HER-Xmrk chimera is a potent transfonning protein equivalent to other tyrosine kinase oncoproteins.
KW  - Physiologische Chemie
KW  - chimeric RTKs
KW  - melanoma
KW  - RTK
KW  - Xiphophorus
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61699
ER  -