Cryo-EM structure of human TMEM45A with a bound 2-Hydroxypalmitate.

The orphan transmembrane protein 45 A (TMEM45A) is highly expressed in keratinocytes as well as cancer cells under hypoxic conditions, where it contributes to metastasis and chemoresistance. The structure of human TMEM45A, determined with single-particle cryo-electron microscopy (cryo-EM) to 3.27 Å, reveals a homotetrameric assembly of seven-transmembrane-helix protomers. The first six transmembrane helices (TMHs) of each protomer assemble to form a central hydrophobic tunnel containing a 2-hydroxypalmitate.