Differential interaction of β2e with phosphoinositides: A comparative study between β2e and MARCKS

Abstract

Voltage-gated calcium (Ca V ) channels are responsible for Ca 2C influx in excitable cells. As one of the auxiliary subunits, the Ca V b subunit plays a pivotal role in the membrane expression and receptor modulation of Ca V channels. In particular, the subcellular localization of the b subunit is critical for determining the biophysical properties of Ca V channels. Recently, we showed that the b2e isotype is tethered to the plasma membrane. Such a feature of b2e is due to the reversible electrostatic interaction with anionic membrane phospholipids. Here, we further explored the membrane interaction property of b2e by comparing it with that of myristoylated alanine-rich C kinase substrate (MARCKS). First, the charge neutralization of the inner leaf of the plasma membrane induced the translocation of both b2e and MARCKS to the cytosol, while the transient depletion of poly-phosphoinositides (poly-PIs) by translocatable pseudojanin (PJ) systems induced the cytosolic translocation of b2e but not MARCKS. Second, the activation of protein kinase C (PKC) induced the translocation of MARCKS but not b2e. We also found that after the cytosolic translocation of MARCKS by receptor activation, depletion of poly-PIs slowed the recovery of MARCKS to the plasma membrane. Together, our data demonstrate that both b2e and MARCKS bind to the membrane through electrostatic interaction but with different binding affinity, and thus, they are differentially regulated by enzymatic degradation of membrane PIs.

The HOOK region of voltage-gated Ca2+ channel β subunits senses and transmits PIP2 signals to the gate

“…6, B and C ). It is known that basic amino acids and aromatic residues are major determinants of the membrane incorporation of peripheral proteins ( Gelb et al, 1999 ; Miranda-Laferte et al, 2014 ; Kim et al, 2015a , b ; Kim and Suh, 2016 ). Thus, we investigated whether mutant forms of B domain peptide (B Ala and Phe Ala ) can interact with liposomes containing anionic lipids.…”

“…9 ). It has been reported that both basic and aromatic residues of the N terminus play essential roles in the electrostatic interaction of the Ca V β2e subunit with the plasma membrane ( Miranda-Laferte et al, 2014 ; Kim et al, 2015a , b ; Kim and Suh, 2016 ). Here, we also found that the interaction of the HOOK region with the plasma membrane depends on both polybasic and hydrophobic residues within the B domain.…”

The hydrophobic nature of a novel membrane interface regulates the enzyme activity of a voltage-sensing phosphatase

“…There are some examples in which aromatic amino acids help proteins insert themselves into membranes. Studies of the membrane-tethered β2 subunit of voltage-gated Ca 2+ channel (Ca V ) suggested that Ca V binds to the plasma membrane through electrostatic and hydrophobic interactions with basic and aromatic residues (Miranda-Laferte et al, 2014; Kim et al, 2015; Kim and Suh, 2016; Park et al, 2017). In a study of phospholipase A 2 (PLA 2 ), tryptophan plays an important role in binding to the plasma membrane, and removal of tryptophan at the interface lowers the affinity of PLA 2 to the membrane (Gelb et al, 1999).…”

Voltage-Sensing Phosphatases: Biophysics, Physiology, and Molecular Engineering

“…A series of studies using Dr-VSP as a molecular tool for acute depletion of PtdIns(4,5)P 2 (85,(87)(88)(89) showed that binding of the ␤-subunit to the cell membrane is a critical determinant for both voltage-dependent inactivation and PtdIns(4,5)P 2 sensitivity and that a NH 2 -terminal region of the ␤-subunit, called the HOOK region, which contains clusters of multiple charged residues, is critical for the membrane interaction of ␤-subunits (139). All these studies were done with heterologously expressed Ca V in mammalian cells.…”