text: Across mammalian species, VMATs have been found to be structurally well conserved; VMAT1s have an overall sequence identity exceeding 80%. However, there exists only a 60% sequence identity between the human VMAT1 and VMAT2.
  VMAT1 is an acidic glycoprotein with an apparent weight of 40 kDa. Although the crystallographic structure has not yet been fully resolved, VMAT1 is known to have either twelve transmembrane domains (TMDs), based on Kyte-Doolittle hydrophobicity scale analysis or ten TMDs, based on MAXHOM alignment.  MAXHOM alignment was determined using the "profile-fed neural network systems from Heidelberg" (PHD) program.  The main difference between these two models arises from the placement of TMDs II and IV in the vesicle lumen or the cytoplasm.