The recent development of sensitivity-enhanced transverse mixing sequences suitable for H detected solid-state NMR experiments enables fast acquisition of multidimensional experiments for protein backbone assignments. These new sequences include two different approaches, Transverse mixing optimal control pulses (TROP) and simplified preservation of equivalent pathways spectroscopy (SPEPS) . Both allow for simultaneous magnetization transfers of two components, similar to the strategies previously developed for solution NMR experiments , which leads to a theoretical increase in the signal-to-noise ratio (SNR) by a factor of √2 per indirect dimension. It is now straight-forward to assemble all sensitivity-enhanced 3D and 4D pulse sequences required to record spectra for assignments of H, N, C and CO chemical shifts. However, in order to unambiguously assign challenging proteins, access to side chain chemical shifts is critical. Total correlation spectroscopy (TOCSY) mixing was shown to be highly efficient for C- C transfers at magic angle spinning (MAS) rates of ≥ 100 kHz MAS and has since then often been applied for side chain assignments of various types of biomolecules . The suitability of different homonuclear mixing sequences for side chain assignments in H detected experiments at MAS rates of 55-100 kHz has recently been thoroughly explored , with the best performing sequences being dipolar recoupling enhancement through amplitude modulation (DREAM) , TOCSY (DIPSI-3) and Total through-bond correlation spectroscopy (TOBSY) (C948 1 ) . It is therefore useful to revisit TOCSY mixing sequences that have been shown to enable sensitivity-enhancement in solution NMR experiments . Here we explore the suitability of DIPSI-3 for sensitivity-enhanced solid-state NMR experiments. We first evaluate the approach by performing C detected solid-state NMR experiments on a C N labelled methionine-leucine-phenylalanine (MLF) powder sample in combination with simulations of polarization transfer dynamics. Next, we show that by using DIPSI-3 for C- C mixing in triple sensitivity-enhanced 4D hCXCANH and hCXCAcoNH experiments (CX represents aliphatic carbon side-chains) we can obtained high quality spectra suitable for side chain assignments in a challenging 30 kDa membrane protein sample, full-length GlpG, in a few days. GlpG is a rhomboid protease that cleaves its substrates within the cell membrane. We have previously investigated the structure and dynamics related to the gating mechanism and inhibitor binding in a truncated version of GlpG (GlpGN) , where the cytosolic domain has been removed. Additionally, crystal structures of GlpGN and solution NMR structures of the isolated cytosolic domain have been solved. The full length protein has, however, not been characterized in detail so far. As a first step towards the full structural and dynamic characterization of GlpG, we focus here on obtaining the chemical shift assignments of a 100% H2O back-exchanged 2 H 13 C 15 N -uniformly labelled protein sample in a lipid bilayer. We combine the sensitivity-enhanced TOCSY spectra with double sensitivityenhanced 3D hCANH and hCONH and triple sensitivity-enhanced 4D hCACONH and hCOCANH spectra. The advantages of using high dimensional (≥ 4D) spectra for assignments of challenging proteins by solid-state NMR have been thoroughly explored in several studies . Since we are performing the experiments on a perdeuterated sample, we mostly expect to achieve C assignments from the TOCSY experiments. However, for most residue types all aliphatic carbon sidechains are available for assignments based on triple sensitivity-enhanced 4D hCXCANH and hCXCAcoNH spectra despite that the initial magnetization pool is limited to back-exchanged protons.