Tyrosine kinase activity is critical for transducing mitogenic signals inside the cells. Many of these tyrosine kinase proteins and receptors undergo auto-phosphorylation for the regulation of their activity (1, 2). Such autophosphorylation takes place at multiple sites and results in to phosphorylation of cellular substrates. The Nyk receptor tyrosine kinase was identified by screening human glioma expression library with an anti-Phosphotyrosine antibody. The same kinase was also independently identified and cloned by Graham and coworkers and they referred it as Mer (3). A chicken homologues for this gene is also identified as c-eyk (4). The Nyk/Mertk/c-eyk are the newest members of the Ufo/Axl family of receptor tyrosine kinases which are characterized by the presence of NCAM-like extra-cellular regions with 2 IgG-like domains juxtaposed with 2 fibronectin III-like regions. It is been shown that MERTK/Nyk has a strong mitogenic and transforming potential by activating PI 3 kinase, PLCgamma, MAP-kinase pathways (5).
The auto-phosphorylation of MERTK was mapped on tryptic peptide containing amino acids 748-755 (CKKIY749SGDY753Y754RQG). The three tyrosine residues lie in the tyrosine kinase domain between sub-domains VII and VIII (6). It has been shown that kinase activity correlates with autophosphorylation of MERTK and that mutation of these tyrosine severely crippled the kinase activity (7). Autophosphorylation of this regions appears to be a common mechanism for several tyrosine kinases, however, the subtle differences in the pattern of phosphorylation was noted in various other kinase systems. It is also notes that preferable substrate for autophosphorylation in MERTK is the tyrosine 754 (7), substitution mutation to Phenylalanine exhibited a 90% decrease in atophosphorylation of MERTK compared to wild type protein.
The receptor tyrosine kinase MERTK protein is a approximately 175-210 kDa protein. The MERTK protein has a tyrosine kinase domain closer to the C-terminal region and putative phosphorylation sites. The Anti-Phospho-MERTK-selective antibody was generated against phosphor-tyrosine containing peptide from a conserved sequence near the C-terminal end that is unique to MERTK/Nyk protein only. Phospho-specific antibodies were isolated on immobilized phosphor and non-phospho antigen affinity matrices. FabGennix International Inc. also have Anti-MERTK selective antibodies as affinity-purified form for confocal, Western blotting and immunocytochemical analyses. FabGennix Inc. will also conjugate antibodies with fluorescent probes upon request at extra charge. FabGennix Inc. also provides antibodies against proteins that are involved in signal transduction, retinal degenerative diseases and against GPCRs. FabGennix Inc employs cyclic peptide methodology for generating antibodies, which results in higher titer and specificity. FabGennix, Int. Inc., will also provide Western blot positive controls for most of these antibodies in ready-to-use buffer for easy identification of respective proteins. Limited quantities of antigens are also available. Please enquire for their availability before ordering.
For research use only, not for diagnostic or therapeutic use.
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