Myristoylation Restricts Orientation of the GRASP Domain on Membranes and Promotes Membrane Tethering
Frank N. Heinrich, Hirsh Nanda, Goh Haw Zan, Collin Bachert, Mathias Loesche, Adam D. Linstedt
The mammalian GRASP proteins are Golgilocalized homotypic membrane tethers that organize Golgi stacks into a long, contiguous ribbon-like structure. It is unknown how GRASPs undergo trans pairing given that cis interactions between the proteins in the plane of the membrane are intrinsically favored. To test the hypothesis that myristoylation of the selfinteracting GRASP domain restricts its orientation on the membrane to favor trans pairing we established an in vitro assay that recapitulates GRASP-dependent membrane tethering and used neutron reflection under these same conditions to determine the orientation of the GRASP domain. In vivo, the membrane association of GRASP proteins is conferred by the simultaneous insertion of an N-terminal myristic acid and binding to a Golgi-associated binding partner. In our assay, the latter contact was replaced using a C-terminal hexa-His moiety, which bound to Ni2+-conjugated lipids incorporated into a substrate-supported bilayer lipid membrane. Non-myristoylated protein lacked a fixed orientation on the membrane and inefficiently tethered liposomes. In contrast, myristoylated GRASP promoted tethering and exhibited a unique membrane complex. Thus, myristoylation restricts the membrane orientation of the GRASP domain favoring interactions in trans for membrane tethering.
, Nanda, H.
, Zan, G.
, Bachert, C.
, Loesche, M.
and Linstedt, A.
Myristoylation Restricts Orientation of the GRASP Domain on Membranes and Promotes Membrane Tethering, Journal of Biological Chemistry, [online], https://doi.org/10.1074/jbc.m113.543561
(Accessed February 29, 2024)