Human platelets contain scinderin, a Ca(2+)-dependent actin filament-severing protein.
A large body of biochemical and morphological evidence suggests that actin polymerizes in response to various stimuli which activate platelets. Previous work has shown the presence in platelets of gelsolin, a Ca(2+)-dependent regulator of actin filament length. This present work demonstrates that human platelets contain scinderin, another Ca(2+)-dependent actin filament-severing protein recently discovered in our laboratory. Extracts prepared from platelets were subjected to DNase-I-Sepharose 4B affinity chromatography. EGTA eluates from the affinity columns contained scinderin as demonstrated by mono and two-dimensional polyacrylamide gel electrophoresis and immunoblotting with scinderin antibodies. The concentration of scinderin in platelets was 75 fmol/mg total protein. This might represent 11% of the total actin filament-severing activity if both proteins are equally potent, on a molar basis, in severing actin filaments. Double staining immunocytochemical studies with antibodies against scinderin and rhodamine phalloidin, a probe for F-actin, also demonstrated the presence of scinderin in platelets. These findings suggest that scinderin may participate in the regulation of platelet actin networks.
Rodríguez Del Castillo
A
A
Department of Pharmacology, Faculty of Medicine, University of Ottawa, Ontario, Canada.
Vitale
M L
ML
Tchakarov
L
L
Trifaró
J M
JM
D000199:Actins / Q000378:metabolism*; D001792:Blood Platelets / Q000737:chemistry; D002118:Calcium / Q000502:physiology*; D018260:Gelsolin; D006801:Humans; D015151:Immunoblotting; D007457:Iodine Radioisotopes; D008840:Microfilament Proteins / Q000097:blood*; D008856:Microscopy, Fluorescence; D013205:Staphylococcal Protein A / Q000737:chemistry
D000199:Actins; D018260:Gelsolin; D007457:Iodine Radioisotopes; D008840:Microfilament Proteins; D013205:Staphylococcal Protein A; C065395:scinderin; D002118:Calcium