The nonconserved N-terminus of protein phosphatases 1 influences its active site.
Protein phosphatase 1 consists of a secondary structure arrangement, conserved in the serine/threonine protein phosphatase gene family, flanked by nonconserved N-terminal and C-terminal domains. The deletion mutant of PP1 with the 8 nonconserved N-terminal residues removed was designated PP1-(9-330). PP1-(9-330) had a higher activity and affinity than PP1 when assayed against four different substrates, and it also demonstrated a 6-fold higher sensitivity to the inhibitor okadaic acid. This suggested that the N-terminal domain suppressed the activity of PP1 and interfered with its inhibition by okadaic acid. The ANS fluorescence intensity of PP1-(9-330) was greater than that of PP1, which implies that the hydrophobic groove running from active site in the truncated PP1 was more hydrophobic than in PP1. Our findings provide evidence that the nonconserved N-terminus of PP1 functions as an important regulatory domain that influences the active site and its pertinent properties.
Xie
Xiujie
X
Department of Biochemistry and Molecular Biology, Beijing Normal University, Beijing Key Lab, Beijing, 100875, People's Republic of China.
Huang
Wei
W
Xue
Chengzhe
C
Wei
Qun
Q
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D020134:Catalytic Domain / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008958:Models, Molecular; D019319:Okadaic Acid / Q000494:pharmacology; D054645:Protein Phosphatase 1 / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity
D017931:DNA Primers; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D019319:Okadaic Acid; D054645:Protein Phosphatase 1