Camelid IgG antibodies have a highly soluble antigen-binding V-domain, known as VHH, or nanobody, due to its size in the nanometer range. Nanobody molecules are a type of miniature, engineered antibody. Antibodies have both "heavy" and "light" chains of amino acids (peptides). Human antibodies have both types, but llamas, alpacas, and other species make antibodies that have only "heavy-chain" peptides. Nanobody molecules are derived from these "heavy-chain-only" peptides, and are around a tenth the size of conventional antibodies.