level of U4/U6.U5 tri-snRNP-associated protein 1 in blood (OBA_2051707, an Ontology of Biological Attributes identifier) is the amount of a U4/U6.U5 tri-snRNP-associated protein 1 when measured in blood. Also known as: blood U4/U6.U5 tri-snRNP-associated protein 1 amount.