Question

Protein phosphatase 1 (PP1) catalyzes a reaction which yields products that regulate cell division; consequently, PP1 is a possible drug target to treat certain types of cancers. The PP1 enzyme cata- lyzes the hydrolysis of a phosphate group from myelin basic protein (MBP). The reaction is shown below:

PP1 MBP-phosphate-→ MBP+P,
The activity of PP1 was measured in the presence and absence of the inhibitor phosphatidic acid (PA). The concentration of PA was 300 nM. vo without PA vo with PA released . (mg/mL) mL"1 . min1) mL-1 . min-1) 0.00381 0.00620 0.00931 0.0140 0.010 0.0209 0.0335 0.0419 0.0838 0.015 0.025 0.050
(a) Use the data provided to construct a Lineweaver-Burk plot for the PP1 enzyme in the presence and absence of PA. What kind of inhibitor is PA?
(b) Report the KM and Vmax values for PP1 in the presence and absence of the inhibitor.

Answer 1

More data is needed to construct a Lineweaver-Burk plot and identify the type of inhibitor PA is, as well as determine KM and Vmax values for PP1. Phospholipase C and its role in signal transduction, and protein phosphorylation's significance in cellular functions, are core concepts relevant to understanding the importance of phosphatase enzymes such as PP1 in biological research.

Step-by-step explanation:

To answer the student's question regarding Protein Phosphatase 1 (PP1) and its inhibition by phosphatidic acid (PA), one would need to plot the given initial velocity (vo) data against the reciprocal substrate concentration [S] in a Lineweaver-Burk plot. Since there is no specific data on substrate concentration or inhibition type, we cannot directly construct the plot nor provide the exact type of inhibitor PA is or the KM and Vmax values. More information is needed.

Meanwhile, the discussion about the enzyme phospholipase C contributes to the understanding of cellular signaling. The hydrolysis of PIP₂ by phospholipase C yields diacylglycerol (DAG) and inositol triphosphate (IP₃), both of which are important second messengers. DAG activates protein kinase C (PKC), while IP₃ releases Ca²⁺ from the endoplasmic reticulum, which further propagates the signal transduction cascade.

Protein phosphorylation is a significant post-translational modification that regulates numerous cellular processes, and protein phosphatases like PP1 play a critical role in reversing phosphorylation, thereby affecting processes such as cell division, signaling pathways, and potentially apoptosis. The PAPE procedure mentioned in the provided information is a technique used to enrich phosphoproteins such as those regulated by PP1, highlighting the importance of protein phosphorylation and dephosphorylation in biological research.

Answer 2

Explanation:8iikk