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Distinctive tissue distribution and phosphorylation of IRSp53 isoforms
Y Okamura-Oho1, T Miyashita, M Yamada
1Department of Genetics, National Children's Medical Research Center, 3-35-31 Taishido, Setagaya, Tokyo, 154-8509, Japan.
Biochemical and Biophysical Research Communications
|December 14, 2001
Summary
Insulin-receptor substrate of 53-kDa protein (IRSp53) isoforms show distinct tissue expression and phosphorylation patterns. L and S forms are in the brain and phosphorylated by insulin, while the T form is in cancer cells and phosphorylated by IGF-I.
Area of Science:
- Molecular Biology
- Cell Biology
- Neuroscience
Background:
- Insulin-receptor substrate of 53-kDa protein (IRSp53) is an adapter protein involved in neurite outgrowth.
- IRSp53 interacts with Rho-family GTPases and the DRPLA protein, linked to dentatorubral-pallidoluysian atrophy (DRPLA).
- Human IRSp53 exists in multiple isoforms with unique C-terminal sequences.
Purpose of the Study:
- To investigate the tissue distribution of IRSp53 isoforms.
- To determine the phosphorylation patterns of IRSp53 isoforms.
- To understand how unique C-terminal sequences influence isoform function.
Main Methods:
- Western blotting using isoform-specific antibodies.
- Analysis of protein expression in various tissues and a cancer cell line.
- Stimulation with insulin and IGF-I to assess phosphorylation.
Main Results:
- The L and S IRSp53 isoforms were detected in brain tissue.
- The T IRSp53 isoform was found in a cancer cell line, not in examined tissues.
- L and S isoforms were phosphorylated by insulin; the T isoform was phosphorylated by IGF-I.
Conclusions:
- IRSp53 isoforms exhibit tissue-specific distribution.
- Isoform-specific C-terminal sequences dictate differential phosphorylation in response to growth factors.
- These findings contribute to understanding IRSp53's role in cellular signaling and disease.