Binds tightly to placental ribonuclease inhibitor and has very low ribonuclease activity. Has potent angiogenic activity. Angiogenin induces vascularization of normal and malignant tissues. Abolishes protein synthesis by specifically hydrolyzing cellular tRNAs. Divalent metal ions, such as Cu2+ and Zn2+, may inhibit the ribonucleolytic activity. Rapidly endocytosed by target cells and translocated to the nucleus where it accumulates in the nucleolus and binds to DNA (By similarity). Serum and milk. Belongs to the pancreatic ribonuclease family.