Related Experiment Video
Updated: Aug 12, 2026

Muscle Receptor Organs in the Crayfish Abdomen: A Student Laboratory Exercise in Proprioception
Published on: November 18, 2010
Ca2+-binding proteins in crayfish abdominal muscle. Evidence for a calmodulin lacking trimethyllysine
Abstract:
A partially combined procedure for the isolation of some Ca2+-binding proteins from crayfish abdominal muscle is described, and some biochemical and biophysical data are reported. Crayfish calmodulin is similar to other calmodulins isolated from animal tissues, with the exception that it does not contain trimethyllysine. Besides calmodulin, an unknown protein is described which also binds to phenyl-Sepharose in a Ca2+-dependent manner. Despite its similarities with respect to subunit molecular weight and isoelectric point with 'sarcoplasmic calcium-binding proteins', its amino acid composition shows no similarities either with these proteins or with calmodulin. Furthermore, it is shown that sarcoplasmic Ca2+-binding proteins do not bind to phenyl-Sepharose under the same conditions.
Related Concept Videos
Muscle Contraction
Actin and Myosin in Muscle Contraction
Muscle Contraction
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Catenins
Catenins in Cell Junctions
Catenins bind to cell adhesion molecules such as cadherins and link them to different cytoskeletal proteins depending on the type of cell junction. At the adherens...
Smooth Muscle Contraction
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...

