FC0030
Ribonuclease (RNase I)  -  RNase inhibitor

Biological function
Human pancreatic RNase is produced by a wide variety of tissues and shows a high endonucleolytic activity and high activities against double-stranded RNA and double- stranded DNA–RNA hybrids. RNase I has been implicated in the regulation of vascular homeostasis and triggers the development of immature dendrites as well as stimulates their production of cytokines.

Structural evidence
The positively charged sidechains R4, K6, R32, R39 and K102 adopt multiple conformations. Chemical exchange (i.e., backbone motion on the microsecond-to-millisecond timescale) is observed for two residues, namely, K102 and H119, which are implicated in activity.

Biochemical evidence
Basic residues, namely R4, K6, R32, R39 and K102, contribute to the augmented enzymatic and biological activities of RNase 1, which are located near but not in the active site.

Mechanism category
competitive binding

Significance
The ability of the side chains of R4, K6, R32, R39 and K102 to adopt multiple conformations is crucial for their binding to two targets, namely, negatively charged membrane components and RNA.

Submitted by
Katalin Kover   kover@science.unideb.hu