Affinity chromatography for purification of the modular protein growth factor receptor-bound protein 2 and development of a screening test for growth factor receptor-bound protein 2 Src homology 3 domain inhibitor using peroxidase-linked ligand

Abstract To identify genes involved in the central regulation of energy balance, we compared hypothalamic mRNA from lean and obese Psammomys obesus, a polygenic model of obesity, using differential display PCR. One mRNA transcript was observed to be elevated in obese, and obese diabetic, P. obesus compared with lean animals and was subsequently found to be increased 4-fold in the hypothalamus of lethal yellow agouti (Ay/a) mice, a murine model of obesity and diabetes. Intracerebroventricular infusion of antisense oligonucleotide targeted to this transcript selectively suppressed its hypothalamic mRNA levels and resulted in loss of body weight in both P. obesus and Sprague Dawley rats. Reductions in body weight were mediated by profoundly reduced food intake without a concomitant reduction in metabolic rate. Yeast two-hybrid screening, and confirmation in mammalian cells by bioluminescence resonance energy transfer analysis, demonstrated that the protein it encodes interacts with endophilins, mediators of synaptic vesicle recycling and receptor endocytosis in the brain. We therefore named this transcript Src homology 3-domain growth factor receptor-bound 2-like (endophilin) interacting protein 1 (SGIP1). SGIP1 encodes a large proline-rich protein that is expressed predominantly in the brain and is highly conserved between species. Together these data suggest that SGIP1 is an important and novel member of the group of neuronal molecules required for the regulation of energy homeostasis.

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The activation mechanism of ACK1 (activated Cdc42-associated tyrosine kinase 1)

Biochemical Journal ◽

10.1042/bj20111575 ◽

2012 ◽

Vol 445 (2) ◽

pp. 255-264 ◽

Cited By ~ 19

Author(s):

Qiong Lin ◽

Jian Wang ◽

Chandra Childress ◽

Wannian Yang

Keyword(s):

Cell Adhesion ◽

Growth Factor ◽

Tyrosine Kinase ◽

Molecular Mechanism ◽

Growth Factor Receptor ◽

Activation Mechanism ◽

Src Homology 3 ◽

Src Homology 3 Domain ◽

Src Homology ◽

Epidermal Growth

ACK [activated Cdc42 (cell division cycle 42)-associated tyrosine kinase; also called TNK2 (tyrosine kinase, non-receptor, 2)] is activated in response to multiple cellular signals, including cell adhesion, growth factor receptors and heterotrimeric G-protein-coupled receptor signalling. However, the molecular mechanism underlying activation of ACK remains largely unclear. In the present study, we demonstrated that interaction of the SH3 (Src homology 3) domain with the EBD [EGFR (epidermal growth factor receptor)-binding domain] in ACK1 forms an auto-inhibition of the kinase activity. Release of this auto-inhibition is a key step for activation of ACK1. Mutation of the SH3 domain caused activation of ACK1, independent of cell adhesion, suggesting that cell adhesion-mediated activation of ACK1 is through releasing the auto-inhibition. A region at the N-terminus of ACK1 (Leu10–Leu14) is essential for cell adhesion-mediated activation. In the activation of ACK1 by EGFR signalling, Grb2 (growth-factor-receptor-bound protein 2) mediates the interaction of ACK1 with EGFR through binding to the EBD and activates ACK1 by releasing the auto-inhibition. Furthermore, we found that mutation of Ser445 to proline caused constitutive activation of ACK1. Taken together, our studies have revealed a novel molecular mechanism underlying activation of ACK1.

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The Small 11-kDa Protein from B19 Parvovirus Binds Growth Factor Receptor-Binding Protein 2 in Vitro in a Src Homology 3 Domain/Ligand-Dependent Manner

Virology ◽

10.1006/viro.2001.1217 ◽

2001 ◽

Vol 291 (2) ◽

pp. 285-291 ◽

Cited By ~ 22

Author(s):

Mannie M.Y. Fan ◽

Lillian Tamburic ◽

Cynthia Shippam-Brett ◽

Darren B. Zagrodney ◽

Caroline R. Astell

Keyword(s):

Growth Factor ◽

Receptor Binding ◽

Growth Factor Receptor ◽

Dependent Manner ◽

Src Homology 3 ◽

B19 Parvovirus ◽

Src Homology 3 Domain ◽

Src Homology ◽

Receptor Binding Protein

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SGIP1α, but Not SGIP1, is an Ortholog of FCHo Proteins and Functions as an Endocytic Regulator

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.801420 ◽

2021 ◽

Vol 9 ◽

Author(s):

Sang-Eun Lee ◽

Eunji Cho ◽

Soomin Jeong ◽

Yejij Song ◽

Seokjo Kang ◽

...

Keyword(s):

Energy Homeostasis ◽

Growth Factor Receptor ◽

Domain Growth ◽

Interacting Protein ◽

Src Homology 3 ◽

Functional Consequences ◽

Src Homology 3 Domain ◽

Src Homology ◽

Growth Factor Receptor Bound

Src homology 3-domain growth factor receptor-bound 2-like interacting protein 1 (SGIP1), originally known as a regulator of energy homeostasis, was later found to be an ortholog of Fer/Cip4 homology domain-only (FCHo) proteins and to function during endocytosis. SGIP1α is a longer splicing variant in mouse brains that contains additional regions in the membrane phospholipid-binding domain (MP) and C-terminal region, but functional consequences with or without additional regions between SGIP1 and SGIP1α remain elusive. Moreover, many previous studies have either inadvertently used SGIP1 instead of SGIP1α or used the different isoforms with or without additional regions indiscriminately, resulting in further confusion. Here, we report that the additional region in the MP is essential for SGIP1α to deform membrane into tubules and for homo-oligomerization, and SGIP1, which lacks this region, fails to perform these functions. Moreover, only SGIP1α rescued endocytic defects caused by FCHo knock-down. Thus, our results indicate that SGIP1α, but not SGIP1, is the functional ortholog of FCHos, and SGIP1 and SGIP1α are not functionally redundant. These findings suggest that caution should be taken in interpreting the role of SGIP1 in endocytosis.

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