Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The specific binding of the microtubule-associated protein 2 (MAP2) to the outer membrane of rat brain mitochondria.

ABSTRACT: Purified mitochondria from rat brain contain microtubule-associated proteins (MAPs) bound to the outer membrane. Studies of binding in vitro performed with microtubules and with purified microtubule proteins showed that mitochondria preferentially interact with the high-molecular-mass MAPs (and not with Tau protein). Incubation of intact mitochondria with Taxol-stabilized microtubules resulted in the selective trapping of both MAPs 1 and 2 on mitochondria, indicating that an interaction between the two organelles occurred through a site on the arm-like projection of MAPs. Two MAP-binding sites were located on intact mitochondria. The lower-affinity MAP2-binding site (Kd = 2 x 10(-7) M) was preserved and enriched in the outer-membrane fraction, whereas the higher-affinity site (Kd = 1 x 10(-9) M) was destroyed after removing the outer membrane with digitonin. Detergent fractionation of mitochondrial outer membranes saturated with MAP2 bound in vitro showed that MAPs are associated with membrane fragments which contain the pore-forming protein (porin). MAP2 also partially prevents the solubilization of porin from outer membrane, indicating a MAP-induced change in the membrane environment of porin. These observations demonstrate the presence of specific MAP-binding sites on the outer membrane, suggesting an association between porin and the membrane domain involved in the cross-linkage between microtubules and mitochondria.

SUBMITTER: Linden M

PROVIDER: S-EPMC1138796 | biostudies-other | 1989 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

MAP2 and tau bind longitudinally along the outer ridges of microtubule protofilaments.

Project description:MAP2 and tau exhibit microtubule-stabilizing activities that are implicated in the development and maintenance of neuronal axons and dendrites. The proteins share a homologous COOH-terminal domain, composed of three or four microtubule binding repeats separated by inter-repeats (IRs). To investigate how MAP2 and tau stabilize microtubules, we calculated 3D maps of microtubules fully decorated with MAP2c or tau using cryo-EM and helical image analysis. Comparing these maps with an undecorated microtubule map revealed additional densities along protofilament ridges on the microtubule exterior, indicating that MAP2c and tau form an ordered structure when they bind microtubules. Localization of undecagold attached to the second IR of MAP2c showed that IRs also lie along the ridges, not between protofilaments. The densities attributable to the microtubule-associated proteins lie in close proximity to helices 11 and 12 and the COOH terminus of tubulin. Our data further suggest that the evolutionarily maintained differences observed in the repeat domain may be important for the specific targeting of different repeats to either alpha or beta tubulin. These results provide strong evidence suggesting that MAP2c and tau stabilize microtubules by binding along individual protofilaments, possibly by bridging the tubulin interfaces.

| S-EPMC2173547 | biostudies-literature

Mitochondria-Associated Degradation Pathway (MAD) Function beyond the Outer Membrane.

Project description:The mitochondria-associated degradation pathway (MAD) mediates ubiquitination and degradation of mitochondrial outer membrane (MOM) proteins by the proteasome. We find that the MAD, but not other quality-control pathways including macroautophagy, mitophagy, or mitochondrial chaperones and proteases, is critical for yeast cellular fitness under conditions of paraquat (PQ)-induced oxidative stress in mitochondria. Specifically, inhibition of the MAD increases PQ-induced defects in growth and mitochondrial quality and decreases chronological lifespan. We use mass spectrometry analysis to identify possible MAD substrates as mitochondrial proteins that exhibit increased ubiquitination in response to PQ treatment and inhibition of the MAD. We identify candidate substrates in the mitochondrial matrix and inner membrane and confirm that two matrix proteins are MAD substrates. Our studies reveal a broader function for the MAD in mitochondrial protein surveillance beyond the MOM and a major role for the MAD in cellular and mitochondrial fitness in response to chronic, low-level oxidative stress in mitochondria.

| S-EPMC7391283 | biostudies-literature

Conserved Lysine Acetylation within the Microtubule-Binding Domain Regulates MAP2/Tau Family Members.

Project description:Lysine acetylation has emerged as a dominant post-translational modification (PTM) regulating tau proteins in Alzheimer's disease (AD) and related tauopathies. Mass spectrometry studies indicate that tau acetylation sites cluster within the microtubule-binding region (MTBR), a region that is highly conserved among tau, MAP2, and MAP4 family members, implying that acetylation could represent a conserved regulatory mechanism for MAPs beyond tau. Here, we combined mass spectrometry, biochemical assays, and cell-based approaches to demonstrate that the tau family members MAP2 and MAP4 are also subject to reversible acetylation. We identify a cluster of lysines in the MAP2 and MAP4 MTBR that undergo CBP-catalyzed acetylation, many of which are conserved in tau. Similar to tau, MAP2 acetylation can occur in a cysteine-dependent auto-regulatory manner in the presence of acetyl-CoA. Furthermore, tubulin reduced MAP2 acetylation, suggesting tubulin binding dictates MAP acetylation status. Taken together, these results uncover a striking conservation of MAP2/Tau family post-translational modifications that could expand our understanding of the dynamic mechanisms regulating microtubules.

| S-EPMC5176320 | biostudies-literature

Phosphorylation of the microtubule-associated protein MAP2 by GTP.

Project description:The chick brain microtubule-associated protein MAP2 can be phosphorylated in vitro to the extent of 12 mol/mol with GTP at the same sites as can be labelled by the cyclic AMP-independent protein kinase utilizing [gamma-32P]ATP as the phosphoryl donor. Consequently, the microtubule protein is chemically modified by the conditions usually employed for studies of microtubule assembly, so that the derived kinetic parameters may not relate to steady-state conditions.

| S-EPMC1144473 | biostudies-other

Variations in in vivo phosphorylation at the proline-rich domain of the microtubule-associated protein 2 (MAP2) during rat brain development.

Project description:Microtubule-associated protein 2 (MAP2) is an in vitro substrate for MAP kinase. Part of the phosphorylation occurs at the C-terminal microtubule-binding domain of the molecule which contains a cluster of putative consensus sites for MAP kinase on a proline-rich region. A peptide with the sequence RTPGTPG-TPSY, located at this region of the molecule, is efficiently phosphorylated by MAP kinase in vitro. An antibody (972) raised against this non-phosphorylated peptide has been used to test for in vivo phosphorylation at the proline-rich domain of the MAP2 molecule. The reaction of purified MAP2 with antibody 972 diminishes after in vitro phosphorylation by MAP kinase and is enhanced after in vitro dephosphorylation by alkaline phosphatase. A fraction of brain MAP2 isolated by iron-chelation affinity chromatography appears to be phosphorylated in vivo at the site recognized by antibody 972. There is some variation in the phosphorylation of MAP2 at the proline-rich region throughout rat brain development. MAP2C is more highly phosphorylated in the developing rat brain, whereas high-molecular-mass MAP2 is more extensively phosphorylated in the adult rat brain.

| S-EPMC1136543 | biostudies-other

The Origin of Mitochondria-Specific Outer Membrane β-Barrels from an Ancestral Bacterial Fragment.

Project description:Outer membrane β-barrels (OMBBs) are toroidal arrays of antiparallel β-strands that span the outer membrane of Gram-negative bacteria and eukaryotic organelles. Although homologous, most families of bacterial OMBBs evolved through the independent amplification of an ancestral ββ-hairpin. In mitochondria, one family (SAM50) has a clear bacterial ancestry; the origin of the other family, consisting of 19-stranded OMBBs found only in mitochondria (MOMBBs), is substantially unclear. In a large-scale comparison of mitochondrial and bacterial OMBBs, we find evidence that the common ancestor of all MOMBBs emerged by the amplification of a double ββ-hairpin of bacterial origin, probably at the time of the Last Eukaryotic Common Ancestor. Thus, MOMBBs are indeed descended from bacterial OMBBs, but their fold formed independently in the proto-mitochondria, possibly in response to the need for a general-purpose polypeptide importer. This occurred by a process of amplification, despite the final fold having a prime number of strands.

| S-EPMC6193526 | biostudies-literature

Mitochondria-associated microRNAs in rat hippocampus following traumatic brain injury.

Project description:Traumatic brain injury (TBI) is a major cause of death and disability. However, the molecular events contributing to the pathogenesis are not well understood. Mitochondria serve as the powerhouse of cells, respond to cellular demands and stressors, and play an essential role in cell signaling, differentiation, and survival. There is clear evidence of compromised mitochondrial function following TBI; however, the underlying mechanisms and consequences are not clear. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression post-transcriptionally, and function as important mediators of neuronal development, synaptic plasticity, and neurodegeneration. Several miRNAs show altered expression following TBI; however, the relevance of mitochondria in these pathways is unknown. Here, we present evidence supporting the association of miRNA with hippocampal mitochondria, as well as changes in mitochondria-associated miRNA expression following a controlled cortical impact (CCI) injury in rats. Specifically, we found that the miRNA processing proteins Argonaute (AGO) and Dicer are present in mitochondria fractions from uninjured rat hippocampus, and immunoprecipitation of AGO associated miRNA from mitochondria suggests the presence of functional RNA-induced silencing complexes. Interestingly, RT-qPCR miRNA array studies revealed that a subset of miRNA is enriched in mitochondria relative to cytoplasm. At 12h following CCI, several miRNAs are significantly altered in hippocampal mitochondria and cytoplasm. In addition, levels of miR-155 and miR-223, both of which play a role in inflammatory processes, are significantly elevated in both cytoplasm and mitochondria. We propose that mitochondria-associated miRNAs may play an important role in regulating the response to TBI.

| S-EPMC4346439 | biostudies-literature

Gender- and region-specific changes in estrogen signaling in aging rat brain mitochondria.

Project description:Recently epidemiological studies suggest females lose neuroprotection from neurodegenerative diseases as they go through menopause. It has been hypothesized that this neuroprotection is hormone-dependent. The current study characterized cell signaling molecules downstream of estrogen receptor beta that are known to play a role in memory, PKC, ERK, and connexin-43, in regions of the brain associated with memory decline in an attempt to elucidate significant changes that occur post-estrus. Total whole cell lysates were compared to isolated mitochondrial protein because mitochondrial function is known to be altered during aging. As hypothesized, protein concentrations differed depending on age, gender, and brain region. Additionally, many of these changes occurred within mitochondria but not within whole cell lysates indicating that these are epigenetic alterations. These findings accentuate the complexity of aging and provide insight into the gender-specific cellular processes that occur throughout this process.

| S-EPMC6128413 | biostudies-literature

Assembly of chick brain MAP2-tubulin microtubule protein. Characterization of the protein and the MAP2-dependent addition of tubulin dimers.

Project description:The principle proteins present in twice-cycled chick brain microtubule protein were characterized. The protein consists of a stoichiometric mixture of MAP2 and tubulin, together with a number of minor components. Its composition remains unaltered after a third cycle of assembly in a buffer supplemented with 67 mM-NaCl, with the exception of the phosphorylation of MAP2 to a low level (congruent to 1 mol.mol-1). The inclusion of 67 mM-NaCl dissociates the MAP2-tubulin oligomers, and restricts the assembly to the MAP2-dependent addition and loss of tubulin dimers, such that the assembly kinetics approximate to a simple pseudo-first-order reaction. The assembled microtubules exhibit dynamic instability, with no evidence for end-to-end annealing.

| S-EPMC1151214 | biostudies-other

Microtubule-associated protein tau in bovine retinal photoreceptor rod outer segments: comparison with brain tau.

Project description:Recent studies have suggested a possible involvement of abnormal tau in some retinal degenerative diseases. The common view in these studies is that these retinal diseases share the mechanism of tau-mediated degenerative diseases in brain and that information about these brain diseases may be directly applied to explain these retinal diseases. Here we collectively examine this view by revealing three basic characteristics of tau in the rod outer segment (ROS) of bovine retinal photoreceptors, i.e., its isoforms, its phosphorylation mode and its interaction with microtubules, and by comparing them with those of brain tau. We find that ROS contains at least four isoforms: three are identical to those in brain and one is unique in ROS. All ROS isoforms, like brain isoforms, are modified with multiple phosphate molecules; however, ROS isoforms show their own specific phosphorylation pattern, and these phosphorylation patterns appear not to be identical to those of brain tau. Interestingly, some ROS isoforms, under the normal conditions, are phosphorylated at the sites identical to those in Alzheimer's patient isoforms. Surprisingly, a large portion of ROS isoforms tightly associates with a membranous component(s) other than microtubules, and this association is independent of their phosphorylation states. These observations strongly suggest that tau plays various roles in ROS and that some of these functions may not be comparable to those of brain tau. We believe that knowledge about tau in the entire retinal network and/or its individual cells are also essential for elucidation of tau-mediated retinal diseases, if any.

| S-EPMC3724453 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data