B2.030 Mitochondrial Structure and Dynamics Flashcards
what are the cellular roles of mitochondria?
oxidative metabolism beta oxidation of fatty acids regulation of apoptosis ca2+ homeostasis regulate redox balance produce intermediates for biosynthesis
what determines the number and size of mitochondria in a cell?
mitochondrial fission/fusion cycle
what is mitophagy?
degradation of mitochondria, a form of autophagy
what is PGC1alpha?
co-transcriptional regulatory factor with central role in regulation of mitochondrial biogenesis (can promote or inhibit)
what factors increase mitochondrial biogenesis?
endurance exercise, caloric restriction, energy deprivation, cold, neuro-hormonal signaling, oxidative damage
what does PGC1alpha activate?
transcription of nuclear and mitochondrial genes leading to new mitochondria
what is DNA polymerase gamma (POLG)?
nuclear encoded enzyme that copies mtDNA genome
POLG mutations can lead to mtDNA instability and large deletions
what is the purpose of mitophagy?
remove damaged mitochondria
which protein is involved in mitophagy?
PINK1 accumulated following mitochondrial damage
what is the function of PINK1?
recruits E3 ubiquitin ligase parkin to ubiquitylate mitochondria to be engulfed by isolation membrane that fuses with lysosomes
what percentage of proteins in mitochondria are coded for in the nuclear genome?
85% (>1000)
what transporters are involved in the import of proteins into the mitochondria?
TOM- translocase of outer membrane -outer membrane receptors -general import port TIM- translocase of inner membrane -TIM23 -TIM22
what is the function of TIM23?
takes in preproteins with n-terminal sequence
transports preproteins into matrix where the presequence is cleaved and a mature protein is formed
what is the function of TIM22?
takes in preproteins with internal signals
integrates preproteins into inner mitochondrial membrane
what enzymes are involved in macromolecular synthesis within the mitochondria?
DNA polymerase gamma- replicates mtDNA
RNA polymerase- transcribes mtDNA
2 rRNA and 22 tRNA- encoded by mtDNA and involved in translation of 13 mRNAs
