INMP, A NOVEL INTRANUCLEAR MATRIX PROTEIN RELATED TO THE FAMILY OF INTERMEDIATE FILAMENT-LIKE PROTEINS - MOLECULAR-CLONING AND SEQUENCE-ANALYSIS

An important step in understanding nuclear structure and its function in replication and gene regulation is the cloning and characterisation of nuclear matrix proteins. A full-length cDNA-clone, encoding a nove l nuclear matrix protein, was isolated from a (lambda gt11 cDNA librar y derived from murine macrophages. The antibody used for the screen wa s raised against a single polypeptide isolated from two-dimensional ge l electrophoresis of nuclear matrix preparations. The cDNA encodes a p rotein of 446 amino acids named INMP for intranuclear matrix protein. INMP displays several salient features, a coiled-coil domain, a leucin e zipper, a number of phosphorylation sites and a putative nuclear loc alisation signal. Sequence homology comparisons indicate that INMP is a unique protein which is evolutionary related to the gene family of i ntermediate filament-like proteins, especially the nuclear lamins.