Fig. 2: The M-Lip domain is a new protein fold that dimerizes.
From: The middle lipin domain adopts a membrane-binding dimeric protein fold
a Sequence alignment of human and mouse lipin M-Lip domains with secondary structure elements above. The asterisk indicates the last residue of the M-Lipxtal domain. Red and yellow boxes indicate identical and positive homology residues. b Structure of a single subunit of the lipin 1 M-Lipxtal domain in three different views. The N- and C-termini are colored blue and red, respectively. c The M-Lipxtal domain forms a dimer with the α3 helices mediating the majority of contacts at the dimer interface. Individual subunits are colored green and cyan. d Crystal structures and superimposition of the near identical lipin 1 and lipin 2 M-Lipxtal domains. e MALS data (left axis) with SEC traces (right axis) for the lipin 1 M-Lipxtal domain reports a MW of 25 kDa, consistent with a dimer (MW of 26 kDa). f SEC profiles of full-length and lipin 1 ΔM-Lip on SEC with gray lines indicating MW standards. Deletion of the M-Lip shifts the elution profile to a smaller apparent MW. g Surface views of the lipin 1 M-Lipxtal domain showing conservation of the dimer interface. h Co-immunoprecipitation of HA-tagged lipins with V5-tagged lipin 1 constructs. Hepa1-6 cells were co-transfected with HA-tagged lipin 1, −2, and −3 and either V5-tagged lipin 1, ΔM-Lip, or ΔM-Lipxtal. Deletion of the ΔM-Lip or ΔM-Lipxtal domains reduced the amount of HA-tagged lipin proteins that co-immunoprecipitated. n = 1 independent experiment. Source data are provided as a Source data file.
