Molecular cloning and functional expression of chromaffin cell scinderin indicates that it belongs to the family of Ca2+-dependent F-actin severing proteins

Scienderin is a Ca⁺-dependent actin filament severing protein present in chromaffin cells, platelets and a variety of secretory cells. It has been suggested that scinderin is involved in chromaffin cell F-actin dynamics and that this actin network controls the delivery of secretory vesicles to plasma membrane exocytotic sites. Moreover, scinderin redistribution and activity may be regulated by pH and Ca²⁺ in resting and stimulated cells. Here we describe the molecular cloning, the nucleotide sequence and the expression of bovine chromaffin cell scinderin cDNA. The fusion protein obtained cross-reacts with native scinderin antibodies and binds phosphatidylserine (PS), phosphatidylinositol 4,5-bisphosphate (PIP₂) and actin in a Ca⁺-dependent manner. Antibodies raised against the fusion protein produced the same cellular staining patterns for scinderin as anti-native scinderin. Nucleotide and amino acid sequence analysis indicate that scinderin has six domains each containing three internal sequence motifs, two actin and two PIP₂ binding sites and has 63 and 53% homology with gelsolin and villin. These data indicate that scinderin is a novel member of the family of Ca²⁺-dependent F-actin severing proteins which includes gelsolin and villin.Abbreviations PIP₂ phosphatidylinositol 4,5 bisphosphate - PKC protein kinase C - Sc scinderin - PS phosphatidyl serine - F-Sc scinderin fusion protein - PCR polymerase chain reaction