Publications by authors named "Anush Bakunts"

Article Synopsis
  • - Polymeric IgM, an important immunoglobulin, has a strong ability to bind antigens and complements, primarily produced as hexamers or pentamers, with the latter containing a protein called the J-chain for enhanced transportation across cell layers.
  • - The study reveals that the J-chain competes with the sixth subunit during IgM assembly and exists in an unstructured form before stabilizing pentamer formation through interactions with newly formed structures.
  • - The process is regulated by a quality control factor known as ERp44, which ensures that only properly assembled IgM is secreted, thereby ensuring effective immune responses.
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The unfolded protein response can switch from a pro-survival to a maladaptive, pro-apoptotic mode. During ER stress, IRE1α sensors dimerize, become phosphorylated, and activate XBP1 splicing, increasing folding capacity in the ER protein factory. The steps that turn on the IRE1α endonuclease activity against endogenous mRNAs during maladaptive ER stress are still unknown.

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The biosynthesis of about one third of the human proteome, including membrane receptors and secreted proteins, occurs in the endoplasmic reticulum (ER). Conditions that perturb ER homeostasis activate the unfolded protein response (UPR). An 'optimistic' UPR output aims at restoring homeostasis by reinforcement of machineries that guarantee efficiency and fidelity of protein biogenesis in the ER.

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We report the site-specific and covalent bioconjugation of fluorescent polymer chains to proteins in live cells using the HaloTag technology. Polymer chains bearing a Halo-ligand precisely located at their α-chain-end were synthesized in a controlled manner owing to the RAFT polymerization process. They were labeled in lateral position by several organic fluorophores such as AlexaFluor 647.

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How endoplasmic reticulum (ER) stress leads to cytotoxicity is ill-defined. Previously we showed that HeLa cells readjust homeostasis upon proteostatically driven ER stress, triggered by inducible bulk expression of secretory immunoglobulin M heavy chain (μ) thanks to the unfolded protein response (UPR; Bakunts et al., 2017).

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Insufficient folding capacity of the endoplasmic reticulum (ER) activates the unfolded protein response (UPR) to restore homeostasis. Yet, how the UPR achieves ER homeostatic readjustment is poorly investigated, as in most studies the ER stress that is elicited cannot be overcome. Here we show that a proteostatic insult, provoked by persistent expression of the secretory heavy chain of immunoglobulin M (µ), is well-tolerated in HeLa cells.

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The unfolded protein response (UPR) allows cells to adjust secretory pathway capacity according to need. Ire1, the endoplasmic reticulum (ER) stress sensor and central activator of the UPR is conserved from the budding yeast to humans. Under ER stress conditions, Ire1 clusters into foci that enable optimal UPR activation.

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Phosphorylated and non-phosphorylated forms of the F0F1-ATPase subunit c from rat liver mitochondria (RLM) were purified and their effect on the opening of the permeability transition pore (mPTP) was investigated. Addition of dephosphorylated subunit c to RLM induced mitochondrial swelling, decreased the membrane potential and reduced the Ca2+ uptake capacity, which was prevented by cyclosporin A. The same effect was observed in the presence of storage subunit c purified from livers of sheep affected with ceroid lipofuscinosis.

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Parvalbumin is a small protein of EF-hand family whose main role is considered to be metal buffering. Recent evidences indicate that parvalbumin also fulfills more complicated functions, which may be determined by the diversity in structural changes in response to the binding of different metal cations. In the present work the conformations of α and β isoforms of pike parvalbumin in the Ca(2+)- and Mg(2+)-loaded state were studied by intrinsic fluorescence, circular dichroism and bis-ANS extrinsic fluorescence.

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Conformational behavior of five homologous proteins, parvalbumins (PAs) from northern pike (alpha and beta isoforms), Baltic cod, and rat (alpha and beta isoforms), was studied by scanning calorimetry, circular dichroism, and bis-ANS fluorescence. The mechanism of the temperature-induced denaturation of these proteins depends dramatically on both the peculiarities of their amino acid sequences and on their interaction with metal ions. For example, the pike alpha-PA melting can be described by two successive two-state transitions with mid-temperatures of 90 and 120 degrees C, suggesting the presence of two thermodynamic domains.

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Parvalbumin (PA) is a muscle and neuronal calcium-binding protein, the major fish and frog allergen. Its characteristic feature is the presence of multiple isoforms with significantly different amino acid sequences. Here we show that the major isoform of northern pike muscle PA (pI 5.

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Recently defined family of intrinsically disordered proteins (IDP) includes proteins lacking rigid tertiary structure meanwhile fulfilling essential biological functions. Here we show that apo-state of pike parvalbumin (alpha- and beta-isoforms, pI 5.0 and 4.

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Recoverin is a member of the neuronal calcium sensor (NCS) family of EF-hand calcium binding proteins. In a visual cycle of photoreceptor cells, recoverin regulates activity of rhodopsin kinase in a Ca2+-dependent manner. Like all members of the NSC family, recoverin contains a conserved cysteine (Cys38) in nonfunctional EF-hand 1.

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It was recently shown that alpha-lactalbumin associated with oleic acid (HAMLET) interacts with core histones thereby triggering apoptosis of tumor cells (J. Biol. Chem.

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