scholarly journals Serine/threonine kinase 16 and MAL2 regulate constitutive secretion of soluble cargo in hepatic cells

2014 ◽  
Vol 463 (2) ◽  
pp. 201-213 ◽  
Author(s):  
Julie G. In ◽  
Anneliese C. Striz ◽  
Antonio Bernad ◽  
Pamela L. Tuma
Keyword(s):  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Hepatic Cells ◽  
Subsequent Degradation ◽  
Constitutive Secretion

This study identifies two novel regulators of constitutive secretion of soluble cargo in polarized hepatic cells. Biochemical and morphological approaches indicate that these proteins function to divert soluble cargo from lysosome delivery and subsequent degradation.

scholarly journals A phyB-PIF1-SPA1 kinase regulatory complex promotes photomorphogenesis in Arabidopsis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Inyup Paik ◽  
Fulu Chen ◽  
Vinh Ngoc Pham ◽  
Ling Zhu ◽  
Jeong-Il Kim ◽  
...  
Keyword(s):  
Red Light ◽  
Kinase Domain ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
C Terminus ◽  
Subsequent Degradation ◽  
Regulatory Complex

Abstract CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) is a highly conserved E3 ubiquitin ligase from plants to animals and acts as a central repressor of photomorphogenesis in plants. SUPPRESSOR OF PHYA-105 1 family members (SPA1-SPA4) directly interact with COP1 and enhance COP1 activity. Despite the presence of a kinase domain at the N-terminus, no COP1-independent role of SPA proteins has been reported. Here we show that SPA1 acts as a serine/threonine kinase and directly phosphorylates PIF1 in vitro and in vivo. SPAs are necessary for the light-induced phosphorylation, ubiquitination and subsequent degradation of PIF1. Moreover, the red/far-red light photoreceptor phyB interacts with SPA1 through its C-terminus and enhances the recruitment of PIF1 for phosphorylation. These data provide a mechanistic view on how the COP1-SPA complexes serve as an example of a cognate kinase-E3 ligase complex that selectively triggers rapid phosphorylation and removal of its substrates, and how phyB modulates this process to promote photomorphogenesis.

Ability of PknA, a mycobacterial eukaryotic-type serine/threonine kinase, to transphosphorylate MurD, a ligase involved in the process of peptidoglycan biosynthesis

2008 ◽  
Vol 415 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Meghna Thakur ◽  
Pradip K. Chakraborti
Keyword(s):  
Protein Kinases ◽  
Solid Phase ◽  
Morphological Changes ◽  
Binding Assays ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Peptidoglycan Biosynthesis ◽  
Vitro Binding ◽  
Solid Phase Binding

Eukaryotic-type serine/threonine protein kinases in bacteria have been implicated in controlling a host of cellular activities. PknA is one of eleven such protein kinases from Mycobacterium tuberculosis which regulates morphological changes associated with cell division. In the present study we provide the evidence for the ability of PknA to transphosphorylate mMurD (mycobacterial UDP-N-acetylmuramoyl-L-alanine:D-glutamate-ligase), the enzyme involved in peptidoglycan biosynthesis. Its co-expression in Escherichia coli along with PknA resulted in phosphorylation of mMurD. Consistent with these observations, results of the solid-phase binding assays revealed a high-affinity in vitro binding between the two proteins. Furthermore, overexpression of m-murD in Mycobacterium smegmatis yielded a phosphorylated protein. The results of the present study therefore point towards the possibility of mMurD being a substrate of PknA.

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