Our appreciation of the scope and influence of second messenger signaling has its origins in pioneering work on the cAMP-dependent protein kinase. Also called protein kinase A (PKA), this holoenzyme exists as a tetramer comprised of a regulatory (R) subunit dimer and two catalytic (C) subunits. Upon binding of two molecules of the second messenger cAMP to each R subunit, a conformational change...

Collagen prolyl 4-hydroxylase (C-P4H) catalyses the formation of 4-hydroxyproline in collagens. Hydroxylation of prolines in –X-Pro-Glysequences is necessary for the formation of stable collagen triple helices. Molecular oxygen, Fe, 2-oxogluterate and ascorbate are required for the reaction [1]. In vertebrates C-P4H is an 2 2 tetramer in which is the catalytic subunit and the subunit is identic...

Previous studies have shown that the small subunit of Xenopus DNA polymerase gamma (pol gammaB) acts as a processivity factor to stimulate the 140 kDa catalytic subunit of human DNA polymerase gamma. A putative human pol gammaB initially identified by analysis of DNA sequence had not been shown to be functional, and appeared to be an incomplete clone. In this paper, we report the cloning of ful...

The two classes of physiological inhibitors of the catalytic subunit of cAMP-dependent protein kinase are the regulatory subunits and the heat-stable protein kinase inhibitors (PKIs), and both share a common mechanism of inhibition. Each has a similar inhibitor site that resembles a peptide substrate, and this occupies the P-3 to P+1 portion of the peptide recognition site. However, in addition...

L-Lactate dehydrogenase from Bifidobacterium longum shows homotropic activation by pyruvate as well as heterotropic activation by fructose 1,6-bisphosphate. Hybrid enzymes were produced from the wild-type subunit and a mutant subunit, whose substrate specificity was altered to that of malate dehydrogenase, and separated to analyze the substrate-induced homotropic activation mechanism. Oxamate, ...

Autophagy is an evolutionarily conserved cell renewal process that depends on phosphatidylinositol 3-phosphate (PtdIns(3)P). In metazoans, autophagy is inhibited by PtdIns(3,4,5)P(3), the product of class IA PI3Ks, which mediates the activation of the Akt-TOR kinase cascade. However, the precise function of class IA PI3Ks in autophagy remains undetermined. Class IA PI3Ks are heterodimeric prote...

Volume 8, issue 6, e02022-17, 2017, https://doi.org/10.1128/mBio.02022-17. The text erroneously referred to the catalytic subunit of FdnGHI as FdnI rather than the correct FdnG, and it refers to the integral membrane, quinone-binding subunit as FdnG instead of FdnI. This reversal of the accepted naming convention of the subunits is consistent throughout the text, figures, and supplemental infor...

This study investigated the mechanisms responsible for the disrupted homeostasis of reduced glutathione (GSH) in aging muscles with stress (14 days of hind-limb unloading [HU]). Adult and old rats were randomized into four groups: weight bearing and 3, 7, and 14 days of HU. Soleus muscles were harvested to investigate the activity or content of enzymes involved in GSH metabolism (utilization an...

Symmetry is an intrinsic property of homo-oligomers. Amine oxidases are multidomain homodimeric enzymes that contain one catalytic site per subunit, and share a high homology degree. In this paper, we investigated, by fluorescence spectroscopy measurements, the conformational dynamics resiliency in solutions two amine oxidases, from lentil seedlings, Euphorbia characias latex, which crystallogr...