APS [for ‘adapter protein with a pleckstrin homology (PH) and Src homology 2 (SH2) domain’] belongs to a family of adapter proteins involved in signalling by the receptors for insulin, insulin-like growth factor 1, platelet-derived growth factor and nerve growth factor. Other members include alternatively spliced SH2-B isoforms (SH2Bα. SH2-Byβ and SH2-Bγ) and Lnk. These have a C-terminal SH2 domain, a central PH domain and an N-terminal proline-rich region. SH2Bα, APS and Lnk have a conserved C-terminal tyrosine phosphorylation site, whereas the alternatively spliced SH2-Bβ and SH2-Bγ have distinct C-termini. There is considerable sequence similarity between APS, SH2-B and Lnk, particularly in the SH2 domain. Both APS and SH2-Bα interact with the insulin-receptor activation loop phosphorylation sites and undergo insulin-stimulated tyrosine phosphorylation, although the phosphorylation of SH2-B is considerably weaker. APS couples c-Cbl to the insulin receptor, resulting in ubiquitination of the insulin receptor. We established cell lines [Chinese hamster ovary (CHO). T-APS and CHO. T-SH2-B cells] overexpressing APS and SH2-Bα to study their roles in insulin receptor signalling. Either adapter protein enhances insulin receptor and ERK (extracellular-signal-regulated kinase) phosphorylation. In CHO. T-APS cells, Akt phosphorylation is observed earlier than in CHO.T-SH2-B cells. Both enhance insulin-stimulated Akt activation but APS seems to cause greater activation. Thus APS and SH2-B have similar effects on insulin receptor signalling, although the effects of SH2-B are independent of its phosphorylation.
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Conference Article| August 01 2001
Functional effects of APS and SH2-B on insulin receptor signalling
T. S. Pillay
T. S. Pillay 1
1Molecular Endocrinology Group, Institute of Cell Signalling and School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2UH, U.K.
1To whom correspondence should be addressed (e-mail firstname.lastname@example.org)
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Z. Ahmed, T. S. Pillay; Functional effects of APS and SH2-B on insulin receptor signalling. Biochem Soc Trans 1 August 2001; 29 (4): 529–534. doi: https://doi.org/10.1042/bst0290529
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