A-Kinase Anchoring Proteins

Langeberg, Lorene K.; Scott, John D.

doi:10.1016/b0-12-443710-9/00611-6

Cited by 7 publications

(11 citation statements)

References 20 publications

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“…Since the in vitro concentrations of these cytosolic heme biosynthetic enzymes were at least 150‐fold higher than those in liver,50 it is unlikely that these proteins bind each other even weakly in vivo. On the other hand, these studies do not rule out the possibility of a transient in vivo complex, possibly mediated by other proteins serving as a scaffold 51…”

Section: Discussionmentioning

confidence: 75%

Human uroporphyrinogen III synthase: NMR‐based mapping of the active site

et al. 2007

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Uroporphyrinogen III synthase (URO-synthase) catalyzes the cyclization and D-ring isomerization of hydroxymethylbilane (HMB) to uroporphyrinogen (URO'gen) III, the cyclic tetrapyrrole and physiologic precursor of heme, chlorophyl, and corrin. The deficient activity of human URO-synthase results in the autosomal recessive cutaneous disorder, congenital erythropoietic porphyria. Mapping of the structural determinants that specify catalysis and, potentially, protein-protein interactions is lacking. To map the active site and assess the enzyme's possible interaction in a complex with hydroxymethylbilane-synthase (HMB-synthase) and/or uroporphyrinogen-decarboxylase (URO-decarboxylase) by NMR, an efficient expression and purification procedure was developed for these cytosolic enzymes of heme biosynthesis that enabled preparation of special isotopically-labeled protein samples for NMR characterization. Using an 800 MHz instrument, assignment of the URO-synthase backbone (13)C(alpha) (100%), (1)H(alpha) (99.6%), and nonproline (1)H(N) and (15)N resonances (94%) was achieved as well as 85% of the side-chain (13)C and (1)H resonances. NMR analyses of URO-synthase titrated with competitive inhibitors N(D)-methyl-1-formylbilane (NMF-bilane) or URO'gen III, revealed resonance perturbations of specific residues lining the cleft between the two major domains of URO synthase that mapped the enzyme's active site. In silico docking of the URO-synthase crystal structure with NMF-bilane and URO'gen III was consistent with the perturbation results and provided a 3D model of the enzyme-inhibitor complex. The absence of chemical shift changes in the (15)N spectrum of URO-synthase mixed with the homogeneous HMB-synthase holoenzyme or URO-decarboxylase precluded occurrence of a stable cytosolic enzyme complex.

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Section: Discussionmentioning

confidence: 75%

Human uroporphyrinogen III synthase: NMR‐based mapping of the active site

et al. 2007

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“…Previous studies have related AKAP95 to proteins such as Eg7, a chromosome-condensing complex component [15], p68 RNA helicase [16], AMY-1, a c-Myc binding protein [17], minichromosome maintenance 2 protein [18], D-and E-type cyclins [19] and phosphodiesterases [20]. These interactions imply roles for AKAP95 in PKA signalling, DNA condensation, transcription and DNA replication [21]. When re-investigating intranuclear AKAP95-distribution, we repeatedly observed the presence of AKAP95 in the nucleolus of human cells.…”

Section: Introductionmentioning

confidence: 99%

A‐kinase anchoring protein AKAP95 is a novel regulator of ribosomal RNA synthesis

et al. 2016

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The RNA polymerase I transcription apparatus acquires and integrates the combined information from multiple cellular signalling cascades to regulate ribosome production essential for cell growth and proliferation. In the present study, we show that a subpopulation of A-kinase anchoring protein 95 (AKAP95) targets the nucleolus during interphase and is involved in regulating rRNA production. We show that AKAP95 co-localizes with the nucleolar upstream binding factor, an essential rRNA transcription factor. Similar to other members of the C 2 H 2 -zinc finger family, we show, using systematic selection and evolution of ligands by exponential enrichment and in vitro binding analysis, that AKAP95 has a preference for GC-rich DNA in vitro, whereas fluorescence recovery after photobleaching analysis reveals AKAP95 to be a highly mobile protein that exhibits RNA polymerase I and II dependent nucleolar trafficking. In line with its GC-binding features, chromatin immunoprecipitation analysis revealed AKAP95 to be associated with ribosomal chromatin in vivo. Manipulation of AKAP95-expression in U2OS cells revealed a reciprocal relationship between the expression of AKAP95 and 47S rRNA. Taken together, our data indicate that AKAP95 is a novel nucleolus-associated protein with a regulatory role on rRNA production.

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“…The members of the AKAP family are structurally diverse but functionally related, and the ability to anchor the PKA holoenzyme via the interaction with PKA regulatory subunits is their common feature. In mammalian cells, there are four genes encoding regulatory subunits, such as RIα, RIβ, RIIα, and RIIβ, and four genes encoding catalytic subunits, such as Cα, Cβ, Cγ, and PrKX . Upon the elevation of the second messenger cAMP level, cAMP molecules bind to the R subunit which leads to the dissociation of the PKA holoenzyme and release of the C subunits that phosphorylate nearby substrates.…”

Section: Introductionmentioning

confidence: 99%

“…Most AKAPs also have scaffolding functions. They interact with other signaling molecules, and by organizing multivalent complexes they provide the integration and dissemination of information within the cell .…”

Section: Introductionmentioning

confidence: 99%

PKA‐binding domain of AKAP8 is essential for direct interaction with DPY30 protein

et al. 2018

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The main function of the A kinase-anchoring proteins (AKAPs) is to target the cyclic AMP-dependent protein kinase A (PKA) to its cellular substrates through the interaction with its regulatory subunits. Besides anchoring of PKA, AKAP8 participates in regulating the histone H3 lysine 4 (H3K4) histone methyltransferase (HMT) complexes. It is also involved in DNA replication, apoptosis, transcriptional silencing of rRNA genes, alternative splicing, and chromatin condensation during mitosis. In this study, we focused on the interaction between AKAP8 and the core subunit of all known H3K4 HMT complexes-DPY30 protein. Here, we demonstrate that the PKA-binding domain of AKAP8 and the C-terminal domain of DPY30, also called Dpy-30 motif, are crucial for the interaction between these proteins. We show that a single amino acid substitution in DPY30 L69D affects its dimerization and completely abolishes its interaction with AKAP8 and another DPY30-binding partner brefeldin A-inhibited guanine nucleotide-exchange protein 1 (BIG1), which is also AKAP domain-containing protein. We further demonstrate that AKAP8 interacts with DPY30 and the RII alpha regulatory subunit of PKA both in the interphase and in mitotic cells, and we show evidences that AKAP8L, a homologue of AKAP8, interacts with core subunits of the H3K4 HMT complexes, which suggests its role as a potential regulator of these complexes. The results presented here reinforce the analogy between AKAP8-RII alpha and AKAP8-DPY30 interactions, postulated before, and improve our understanding of the complexity of the cellular functions of the AKAP8 protein.Abbreviations AKAP8, A-kinase anchoring protein 8; AKAP8L, A-kinase anchoring protein 8 like; ASH2L, absent, small, or homeotic 2-like protein; BAP18, BPTF-associated protein of 18 kDa; BIG1, brefeldin A-inhibited guanine nucleotide-exchange protein; co-IP, co-immunoprecipitation; DBM, DPY30-binding motif; GST, glutathione S-transferase; H3K4, histone H3 lysine 4; HDAC3, histone deacetylase 3; HEK293, human embryonic kidney 293 cell line; His-tag, polyhistidine-tag; HMT, histone methyltransferase; Kif2A, kinesin family member 2A; KMT, histone lysine methyltransferase; MLL, mixed lineage leukemia; PI, propidium iodide; PKA, cAMP-dependent protein kinase; PRKAR2a, protein kinase cAMP-dependent type II regulatory subunit alpha; RbBP5, retinoblastoma-binding protein 5; RIIa, cAMP-dependent protein kinase type IIalpha regulatory subunit; SAC, spindle assembly checkpoint; TAP tag, tandem affinity purification tag; TPR, translocated promoter region protein; WB, Western blot; WDR5, WD repeat domain 5; WRAD, WDR5-RbBP5-ASH2L-DPY30 complex.

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A-Kinase Anchoring Proteins

Cited by 7 publications

References 20 publications

Human uroporphyrinogen III synthase: NMR‐based mapping of the active site

Human uroporphyrinogen III synthase: NMR‐based mapping of the active site

A‐kinase anchoring protein AKAP95 is a novel regulator of ribosomal RNA synthesis

PKA‐binding domain of AKAP8 is essential for direct interaction with DPY30 protein

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