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Related Concept Videos

Amino Acid Biosynthetic Pathways01:29

Amino Acid Biosynthetic Pathways

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Amino acid biosynthesis is essential for cell growth, protein synthesis, and metabolic regulation. Cells generate essential and non-essential amino acids from metabolic intermediates to sustain vital biological functions. These intermediates originate from key metabolic pathways: glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway. Important precursors include α-ketoglutarate, pyruvate, oxaloacetate, phosphoenolpyruvate, and erythrose-4-phosphate, which...
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Biosynthesis of Nucleic Acids01:28

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Nucleic acid biosynthesis is a fundamental biochemical process that produces the purine and pyrimidine nucleotides essential for DNA and RNA synthesis. This pathway maintains a balanced nucleotide pool, preventing imbalances that could jeopardize genetic integrity and cellular function. Given the crucial role of nucleotides, their synthesis is tightly regulated to ensure proper cellular homeostasis.Purine BiosynthesisThe biosynthesis of purine nucleotides begins with ribose-5-phosphate, a...
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Translocation of Proteins into the Mitochondria01:19

Translocation of Proteins into the Mitochondria

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Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
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Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70  chaperones are targetted to TOM20-TOM22 receptor complexes.
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Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
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Porin Insertion in the Outer Mitochondrial Membrane01:12

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Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
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Mitochondrial NADP(H) generation is essential for proline biosynthesis.

Jiajun Zhu1, Simon Schwörer1, Mirela Berisa2

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Science (New York, N.Y.)
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This summary is machine-generated.

Mitochondrial NAD kinase 2 (NADK2) generates NADP(H) essential for proline biosynthesis and collagen production. Its absence impairs cell growth, which proline supplementation rescues.

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Area of Science:

  • Biochemistry
  • Cell Biology
  • Metabolic Regulation

Background:

  • Nicotinamide adenine dinucleotide phosphate (NADP+) and its reduced form (NADPH) are crucial coenzymes for reductive metabolism.
  • Mitochondrial NADP(H) homeostasis is vital for cellular functions, with NAD kinase 2 (NADK2) identified as a key producer.

Purpose of the Study:

  • To investigate the specific role of mitochondrial NADP(H) generated by NADK2 in cellular metabolism and proliferation.
  • To elucidate the impact of NADK2 deficiency on key metabolic pathways and cellular functions.

Main Methods:

  • Utilized human cell lines with NADK2 deletion.
  • Assessed mitochondrial folate and tricarboxylic acid cycle activity.
  • Monitored cell proliferation, oxidative stress, proline biosynthesis, and collagen production.

Main Results:

  • NADK2 deletion impaired cell proliferation in minimal medium, a defect rescued by proline supplementation.
  • Mitochondrial NADP(H) generation by NADK2 is essential for glutamate reduction and subsequent proline biosynthesis.
  • NADP(H) availability in mitochondria influences collagen protein synthesis in mesenchymal cells.

Conclusions:

  • Mitochondrial NADK2-dependent NADP(H) production is critical for proline biosynthesis, supporting cytosolic protein synthesis.
  • The mitochondrial NADP(H) pool plays a significant role in collagen production by mesenchymal cells.
  • NADK2 is a key regulator of cellular growth and biosynthetic processes through its control of mitochondrial NADP(H).