Nesprin-2 Interacts with Condensin Component SMC2

Figure 1

Characterization of the SMC domain of Nesprin-2. (a) Schematic of Nesprin-2 (not drawn to scale). The location of the SMC domain (spectrin repeats 11–13) and the C-terminal spectrin repeats (53–56) is shown. Epitopes of antibodies used are indicated above the schematic. ABD, actin binding domain; ovals, spectrin repeats. The spectrin repeat domain starts at position 308. (b) Sequence comparison of the Nesprin-2-SMC domain with coiled-coil regions of SMC2 and SMC4. The sequence comparison was performed using LALIGN, the Pairwise Sequence Alignment tool from EMBL-EBI (https://www.ebi.ac.uk/Tools/psa/lalign/). Nesprin-2 (NCBI GenBank accession number AF435011.1), SMC2 (NCBI GenBank accession number O95347.2), and SMC4 (NCBI GenBank accession number Q8WXH0.3) were used.  :, identical amino acid;  ., conservative substitution. (c) Analysis of Nesprin-2-SMC by gel filtration chromatography. UV traces of the elution profile are shown. Nesprin-2 SMC (calculated molecular weight 39 kDa). Molecular weight markers were ovalbumin (43 kDa), conalbumin (75 kDa), and aldolase (158 kDa). (d) Analysis of chemically crosslinked Nesprin-2-SMC. Zero-length cross-linking reagent EDC (1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride) was used at decreasing concentrations. The proteins were separated by SDS-PAGE (10% acrylamide) and stained with Coomassie Blue. (e) Schematic representation of Myc-tagged Nesprin-2-SMC polypeptides. Amino acid positions refer to human Nesprin-2 giant (accession number AF435011.1). (f) Interaction of GST-Nesprin-2-SMC with individual Myc-tagged spectrin repeats derived from Nesprin-2-SMC and expressed in COS7 cells. GST-Nesprin-2-SMC was used for pulldown (right panel). Western blots were probed with mAb 9E10 specific for Myc. Asterisk, endogenous Myc [25]. (g) Specificity of the Nesprin-2-SMC interaction. Myc-SR53–56 expressed in COS7 cells was used for pulldowns with GST for control and GST-Nesprin-2-SMC. COS7 and COS7 Myc-SR53–56 represent whole cell lysates. The Ponceau S stained blot and the corresponding blot probed with mAb 9E10 are shown. MW, molecular weight marker (from top to bottom: 200, 130, 100, 70, 55, 35, and 25 kDa).

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