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Molecular cloning of a truncated p62Dok1 isoform, p22Dok(del)
P Hubert1, V Ferreira, P Debre
1Laboratoire d'Immunologie Cellulaire, CNRS UMR 7627, Paris, France. huberth@ccr.jussieu.fr
Abstract:
The p21Ras GTPase activating protein-associated 62-kDa protein, p62Dok1, is an early substrate of various tyrosine phosphorylation pathways. Its recent cloning in human myeloid cells and in murine pre-B cells revealed an N-terminal pleckstrin-homology domain and a tyrosine- and proline-rich C-terminal tail in its sequence. Here, we characterized a new 1261-bp cDNA identical to that of p62Dok1, but with a central 185-bp deletion (bp 456-640). This induced a frameshift leading to a premature stop codon. The deduced protein, designated p22Dok(del), corresponded to a truncated p62Dok1 isoform of 177 amino acids that can be expressed both in vitro and in vivo with an apparent molecular mass of 22 kDa. This newly identified molecule was composed of the N-terminal PH domain of p62Dok1 followed by a new 25-amino acid C-terminal sequence containing a typical class II proline-rich motif, suggesting a specific role for p22Dok(del) in signal transduction pathways.
Insights
Researchers identified a new truncated protein isoform, p22Dok(del), derived from the p62Dok1 gene. This isoform contains a key signaling domain, suggesting a novel role in cellular pathways.
Area of Science:
- Molecular Biology
- Cell Signaling
Background:
- p62Dok1 is a 62-kDa protein associated with p21Ras GTPase activating protein.
- It acts as an early substrate in tyrosine phosphorylation pathways.
- p62Dok1 possesses an N-terminal pleckstrin-homology (PH) domain and a C-terminal tail rich in tyrosine and proline.
Purpose of the Study:
- To characterize a newly identified cDNA variant of p62Dok1.
- To investigate the structure and potential function of the deduced truncated protein.
Main Methods:
- cDNA sequencing and analysis.
- In vitro and in vivo expression studies.
- Protein characterization through molecular mass determination.
Main Results:
- A novel 1261-bp cDNA with a 185-bp deletion (bp 456-640) was identified, identical to p62Dok1 otherwise.
- This deletion induced a frameshift, resulting in a premature stop codon.
- A truncated isoform, p22Dok(del), of 177 amino acids (22 kDa) was expressed.
- p22Dok(del) retains the N-terminal PH domain and gains a novel 25-amino acid C-terminus with a proline-rich motif.
Conclusions:
- A novel p62Dok1 isoform, p22Dok(del), has been identified.
- The presence of the PH domain and a proline-rich motif suggests a specific role for p22Dok(del) in signal transduction.