Akt2 phosphorylates Synip to regulate docking and fusion of GLUT4-containing vesicles

We have identified an unusual potential dual Akt/protein kinase B consensus phosphorylation motif in the protein Synip (RxKxRS97xS99). Surprisingly, serine 97 is not appreciably phosphorylated, whereas serine 99 is only a specific substrate for Akt2 but not Akt1 or Akt3. Although wild-type Synip (WT-Synip) undergoes an insulin-stimulated dissociation from Syntaxin4, the Synip serine 99 to phenylalanine mutant (S99F-Synip) is resistant to Akt2 phosphorylation and fails to display insulin-stimulated Syntaxin4 dissociation. Furthermore, overexpression of WT-Synip in 3T3L1 adipocytes had no effect on insulin-stimulated recruitment of glucose transporter 4 (GLUT4) to the plasma membrane, whereas overexpression of S99F-Synip functioned in a dominant-interfering manner by preventing insulin-stimulated GLUT4 recruitment and plasma membrane fusion. These data demonstrate that insulin activation of Akt2 specifically regulates the docking/fusion step of GLUT4-containing vesicles at the plasma membrane through the regulation of Synip phosphorylation and Synip–Syntaxin4 interaction

Renal Threshold for Glucose Re-Absorption in Patients with Latent Autoimmune Diabetes of Adults is Similar to That of Patients with Type 1 Diabetes Mellitus but Lower than That of Patients with Type 2 Diabetes Mellitus

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Recovery from radiation-induced degradation in InGaP solar cells by light soaking

In this paper, we report that InGaP solar cells irradiated with electrons exhibit a significant recovery of open-circuit voltage after AM0 light soaking. The soaking-light intensity dependence of defect reduction and the change in the carrier concentration profile upon light soaking suggests that the recombination of photogenerated carriers contributes to the recovery. Because 0.2MeV electrons are only responsible for phosphorus recoil in InGaP, the absence of correlation between the activation energy for voltage recovery and the electron irradiation energies of 0.2, 0.4, and 1MeV implies that the annihilation of radiation-induced phosphorus-related defects contributes to the recovery

Radiation Response of Negative Gate Biased SiC MOSFETs

Silicon carbide (SiC) metal-oxide-semiconductor field effect transistors (MOSFETs) are expected as power electronic devices for high radiative conditions, including nuclear plants and space. Radiation response of commercial-grade prototype SiC MOSFETs with applying the gate bias is of interest, in terms of installation of the device in robots or sensors working under such radioactive circumstances. Due to gamma-rays irradiation, the threshold voltages (Vth) of samples with un- and negative-biased up to -4.5 V slightly shift toward the negative voltage side. In contrast, the positive bias of 2.25 V shifts Vth more negatively. Positive charge densities trapped in the gate oxide of un- and positive-biased samples increased with increasing dose. However, no significant increase was observed for negative-biased samples of -2.25 and -4.5 V. We calculated characteristic parameters for the accumulation of holes in the gate oxide, sigmapJp which is defined as the product of current density due to holes generated by irradiation and capture cross section for a hole in a trap, and it is lower for these negative biased samples compared with the unbiased case. Application of appropriate negative gate biases to SiC MOSFETs during irradiation suppresses accumulation of positive charges in the gate oxide and negative shift of Vth, due to irradiation