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Examines the interactions of the second RNA-binding domain of the Drosophila sex-lethal protein with the transformer pre-messenger RNA polyuridine tract and 3' splice-site sequences. Significance of the chemical-shift perturbations; Identification of a characteristic alipathic residue of the RNA-binding domain of sex-lethal.

Autophagy rids cells of unwanted organelles and recovers nutrients during nutrient deprivation. Microtubule-associated protein 1 light chain 3 (LC3) is recruited to autophagosomes. Here, we study the dynamics of mitochondrial autophagy (mitophagy) in transgenic GFP-LC3 mouse hepatocytes co-loaded with tetramethylrhodamine methylester (TMRM), Lysotracker Red (LTR) or/and PicoGreen (Pico). During nutrient deprivation in Krebs-Ringer HEPES buffer with glucagon (KRH/G), GFP-LC3 (green) rings formed as small green dots decreased. The dots near mitochondria grew into crescents that sequestered TMRM-labeled mitochondria into GFP-LC3 rings in 6 to 12 min. GFP-LC3 sequestered entire mitochondria (42.4%) or portions taken after fission from the ends (43.1%) or middle (9.1%) At completion of sequestration, mitochondria depolarized (loss of TMRM). GFP-LC3 rings acidified (took up LTR) after another 5 min. Pico-labeled mtDNA became entrapped within LTR-labeled autophagosomes and disappeared during lysosomal digestion. In conclusion, LC3-containing membranes envelope all or parts of individual mitochondria during nutrient deprivation-induced mitophagy. Mitochondria then depolarize, which is followed by autophagosomal acidification and digestion. Mitophagy appears to be an important mechanism for mtDNA turnover. [ABSTRACT FROM AUTHOR]