Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1984 Apr 10;798(2):252-9.
doi: 10.1016/0304-4165(84)90313-1.

Limited proteolysis of bovine lens alpha-crystallin by calpain, a Ca2+-dependent cysteine proteinase, isolated from the same tissue

H Yoshida, T Murachi, I Tsukahara

Limited proteolysis of bovine lens alpha-crystallin by calpain, a Ca2+-dependent cysteine proteinase, isolated from the same tissue

H Yoshida et al. Biochim Biophys Acta. .

Abstract

A Ca2+-dependent cysteine proteinase (calpain, EC 3.4.22.17) was found in the cystosolic fraction of bovine lens and purified to apparent homogeneity. The purified enzyme required 1 mM Ca2+ for its full activation and was composed of two subunits of Mr 80 000 and 29 000 as demonstrated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS). This enzyme, when activated by Ca2+, degraded both A- and B-chains of alpha-crystallin, which were isolated also from bovine lens. SDS-gel electrophoresis of the digest revealed that the A-chain (Mr 19 500) was broken down to produce an 18-kDa polypeptide fragment and the B-chain (Mr 22 500) to produce a 19.5-kDa polypeptide fragment. No further cleavage occurred even upon prolonged incubation or after the second addition of the enzyme, indicating the uniquely limited proteolysis of each chain protein. The existence of calpastatin, an endogenous inhibitor protein specific for calpain, was also demonstrated in bovine lens cytosol.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

Publication types

LinkOut - more resources