Molecular and Biochemical Characterization of the Human trk Proto-Oncogene

Abstract

Molecular analysis of the human trk oncogene, a transforming gene isolated from a colon carcinoma biopsy, revealed the existence of a novel member of the tyrosine kinase gene family. This locus, which we now designate the trk proto-oncogene, codes for a protein of 790 amino acid residues that has several features characteristic of cell surface receptors. They include (i) a 32-amino-acid-long putative signal peptide, (ii) an amino-terminal moiety (residues 33 to 407) rich in consensus sites for N-glycosylation, (iii) a transmembrane domain, (iv) a kinase catalytic region highly related to that of other tyrosine kinases, and (v) a very short (15 residue) carboxy-terminal tail. Residues 1 to 392 were absent in the trk oncogene, as they were replaced by tropomyosin sequences. However, no other differences were found between the transforming and nontransforming trk alleles (residues 392 to 790), suggesting that no additional mutations are required to activate the transforming potential of this gene. The human trk proto-oncogene codes for a 140,000-dalton glycoprotein, designated gp140proto-trk. However, its primary translational product is a 110,000-dalton glycoprotein which becomes immediately glycosylated, presumably during its translocation into the endoplasmic reticulum. This molecule, designated gp110proto-trk, is further glycosylated to yield the mature form, gp140proto-trk. Both gp110proto-trk and gp140proto-trk proteins possess in vitro kinase activity specific for tyrosine residues. Finally, iodination of intact NIH 3T3 cells expressing trk proto-oncogene products indicated that only the mature form, gp140proto-trk, cross the plasma membrane, becoming exposed to the outside of the cell. These results indicate that the product of the human trk locus is a novel tyrosine kinase cell surface receptor for an as yet unknown ligand.

Components of the NGF signaling complex are altered in mdx mouse superior cervical ganglion and its target organs

“…The antibody directed against TrkA revealed two bands at about 140 kDa and 110 kDa (Fig. 2A), corresponding to differently glycosylated forms of the receptor (Martin-Zanca et al, 1989), the highest of which represents the fully glycosylated membrane-bound receptor (Mischel et al, 2002). Densitometric analysis (Fig.…”

Endogenous Interleukin 1 Alpha Must Be Transported to the Nucleus To Exert Its Activity in Human Endothelial Cells

“…tEC represent a particularly convenient experimental model for this purpose because they do not express detectable levels of IL-lao (25). Since IL-lot exists as a precursor (IL-11-271) and as a truncated form (IL-1113-271) (8), we generated the corresponding fragments by PCR and inserted them into eukaryotic expression vector pMEXneo (29) to attain high-level constitutive expression of the two forms of IL-lao. pMEXneo-IL-11-27, and pMEXneo-IL-1113-271 were transfected into tEC via calcium phosphate precipitation (48).…”

The Challenge and Opportunity of NTRK Inhibitors in Non-Small Cell Lung Cancer

“…While NTRK mutations, splice variants, and deletions can be seen in some tumor types, these alterations do not typically benefit from targeted therapy. Thus, this manuscript will focus on NTRK fusions as these are the ones associated with response to NTRK-Identification of NTRK as an oncogene in human colorectal carcinoma 1982 [1] Isolation of cDNA of the NTRK1 proto-oncogene 1989 [2] Gene mapping of NTRK1, NTRK2, and NTRK3 to human chromosomes 1q22, 9q22, and 15q25 by FISH 1997 [6] The first generation NTRK inhibitors entered clinical trials…”

“…NTRK1 was first identified as an oncogene in 1982 [ 1 ], and the cDNA of the NTRK1 proto-oncogene was isolated in 1989 [ 2 ]. In 1991, TRKA was found expressed in the nervous system.…”