Specifically hydroxylates an Asp or Asn residue in certain epidermal growth factor-like (EGF) domains of a number of proteins. 2-oxoglutarate + L-aspartyl-[protein] + O2 = 3-hydroxy-L-aspartyl-[protein] + CO2 + succinate Monomer. Isoform 2 interacts with CASQ2. Isoform 1 is detected in heart, liver and ovary (at protein level). Detected in heart ventricle. Isoform 1 is widely expressed. Isoform 2 is detected in heart and skeletal muscle. Strongly expressed in the snout, limbs and eye of 11.5 dpc and 12 dpc. Strong localization of the protein in the lens of the developing eye at all three stages. Selective disruption of isoform 1 abolishes liver aspartyl beta-hydroxylase activity, but does not affect the expression of isoform 2. Mice lacking isoform 1 have normal blood chemistry, do not present blood coagulation defects and appear more or less normal, except for shorter snouts, mild defects of the palate ridges, syndactily due to fusion of soft tissues and reduced litter size from mutant females, while male fertility appears normal. Mice lacking isoform 2 show no visible phenotype. Belongs to the aspartyl/asparaginyl beta-hydroxylase family.