GRAM domain containing 1B, also known as GRAMD1B, Aster-B and KIAA1201, is a cholesterol transport protein that is encoded by the GRAMD1B gene. It contains a transmembrane region and two domains of known function; the GRAM domain and a VASt domain. It is anchored to the endoplasmic reticulum. This highly conserved gene is found in a variety of vertebrates and invertebrates. Homologs (Lam/Ltc proteins) are found in yeast.