A hydrophilic lamin-binding domain from the Drosophila YA protein can target proteins to the nuclear envelope

The nuclear lamina provides an architectural framework for the nuclear envelope and an attachment site for interphase chromatin. In Drosophila eggs and early embryos its major constituent, lamin Dm₀, interacts with a lamina protein called YA. When the lamin-interaction region of YA is deleted, YA still enters nuclei but fails to localize to nuclear envelopes, suggesting that lamin interaction targets YA to the nuclear envelope. Here, we show that C-terminal lamin-interacting region of YA is sufficient to target the heterologous soluble protein GFP-NLS to the nuclear periphery in Drosophila tissue culture cells. Yeast two-hybrid analysis and transient transfection assays further defined this domain: residues 556-696 of YA are sufficient for both lamin Dm₀ interaction and the targeting of GFP-NLS to the nuclear periphery. This region of YA is hydrophilic and lacks any transmembrane domain or known membrane-targeting motifs. We propose that the localization of YA to the nuclear lamina involves interaction with polymerized lamin Dm₀ mediated by the lamin-targeting domain of YA. This hydrophilic YA domain might provide a useful molecular tool for targeting heterologous non-membrane-associated proteins to the nuclear envelope.