Sandbox Reserved 1766: Difference between revisions

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The protein phosphatase 1 catalytic (PP1C) subunit contains the catalytic site of the complex which dephosphorylates the N-terminal phosphoserine (NTpS) of RAF.<ref name="Liau">PMID: 35768504</ref> When PP1C is bound to the surface formed between SHOC2 and MRAS, the active site is exposed and fully accessible for the substrate to bind in the holoenzyme complex.<ref name="Hauseman">PMID:35830882</ref> PP1C cannot act independently from the SMP complex because it lacks intrinsic substrate selectivity.<ref name="Liau">PMID: 35768504</ref> Therefore, PP1C requires the presence of SHOC2 and MRAS to function properly, whereas SHOC2 and MRAS may interact in a binary complex without the presence of PP1C.<ref name="Hauseman">PMID:35830882</ref> SMP complex formation is initially mediated by SHOC2 and PP1C, then stabilized by the GTP interactions in MRAS and SHOC2.<ref name="Kwon">PMID: 35831509</ref>  
The protein phosphatase 1 catalytic (PP1C) subunit contains the catalytic site of the complex which dephosphorylates the N-terminal phosphoserine (NTpS) of RAF.<ref name="Liau">PMID: 35768504</ref> When PP1C is bound to the surface formed between SHOC2 and MRAS, the active site is exposed and fully accessible for the substrate to bind in the holoenzyme complex.<ref name="Hauseman">PMID:35830882</ref> PP1C cannot act independently from the SMP complex because it lacks intrinsic substrate selectivity.<ref name="Liau">PMID: 35768504</ref> Therefore, PP1C requires the presence of SHOC2 and MRAS to function properly, whereas SHOC2 and MRAS may interact in a binary complex without the presence of PP1C.<ref name="Hauseman">PMID:35830882</ref> SMP complex formation is initially mediated by SHOC2 and PP1C, then stabilized by the GTP interactions in MRAS and SHOC2.<ref name="Kwon">PMID: 35831509</ref>  


PP1C activity is regulated by PP1C-binding regulatory proteins.<ref name="Hauseman">PMID:35830882</ref> The regulatory proteins may bind to small motifs in PP1C, like RVXF.<ref name="Liau">PMID: 35768504</ref> The RVXF motif is located in PP1C through the N-terminal disordered region.<ref name="Kwon">PMID: 35831509</ref>  
PP1C activity is regulated by short linear interaction motifs or PP1C-binding regulatory proteins.<ref name="Hauseman">PMID:35830882</ref> The regulatory proteins bind to small motifs in PP1C, like RVXF.<ref name="Liau">PMID: 35768504</ref> The RVXF motif is located in PP1C through the N-terminal disordered region.<ref name="Kwon">PMID: 35831509</ref>  
 
There is a direct interaction between the RVXF motif of SHOC2 and the RVXF-binding pocket of PP1C.<ref name="Hauseman">PMID:35830882</ref>
 
SHOC2 has a RVxF binding motif that interacts with the PP1C RVxF binding site. The N-terminal loop of SHOC2 interacts with the RVxF binding site of PP1C, highlighting the structure and function connection of the complex. RVxF allows PP1C substrates to bind, whereas RAF has the RVxF motif, so it can bind to the hydrophobic region of SHOC2, allowing for greater specificity. Additionally, PP1C and SHOC2 do not change conformationally upon the binding of GTP, but rather they are inactive when RAS is bound to GDP due to steric strain. <scene name='95/952694/Pp1coverlay/3'>PP1C retains the same structure</scene> with or without binding to the SMP complex as PP1C retains its enzymatic function independently.<ref name="Liau">PMID: 35768504</ref>.
 


**FROM THE INITIAL FIRST DRAFT: SHOC2 has a RVxF binding motif that interacts with the PP1C RVxF binding site. The N-terminal loop of SHOC2 interacts with the RVxF binding site of PP1C, highlighting the structure and function connection of the complex. RVxF allows PP1C substrates to bind, whereas RAF has the RVxF motif, so it can bind to the hydrophobic region of SHOC2, allowing for greater specificity. Additionally, PP1C and SHOC2 do not change conformationally upon the binding of GTP, but rather they are inactive when RAS is bound to GDP due to steric strain. <scene name='95/952694/Pp1coverlay/3'>PP1C retains the same structure</scene> with or without binding to the SMP complex as PP1C retains its enzymatic function independently.<ref name="Liau">PMID: 35768504</ref>




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