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Sterols are essential components of cellular membranes and shape their biophysical properties. The recently discovered family of Lipid transfer proteins Anchored at Membrane contact sites (LAMs) has been suggested to carry out intracellular sterol traffic using StART-like domains. Here, we studied the second StART-like domain of Lam4p from S. cerevisiae by NMR. We show that NMR data are consistent with the StART-like domain structure, and that several functionally important regions within the domain exhibit significant conformational dynamics. NMR titration experiments confirm sterol binding to the canonical sterol-binding site and suggest a role of membrane interactions on the thermodynamics and kinetics of sterol binding.

A new solid-state NMR method is presented for estimating homonuclear dipole-dipole couplings for selected groups of nuclear spins in a multiple-spin coupled network. The methodology combines off-magic-angle spinning, frequency selective spin echoes, and multiple quantum filtering. The new method is insensitive to incoherent relaxation effects and may be used to estimate weak couplings. Internuclear (13)C-(13)C couplings are estimated in uniformly (13)C-labelled l-Histidine·HCl·H(2)O. Weak intermolecular couplings between (13)C nuclei separated by distances exceeding 6 Å are estimated.

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