The following text describes a protein:
Function:
Dynamin-related GTPase that is essential for normal mitochondrial morphology by mediating fusion of the mitochondrial inner membranes, regulating cristae morphology and maintaining respiratory chain function. Exists in two forms: the transmembrane, long form (Dynamin-like GTPase MGM1, long form; L-MGM1), which is tethered to the inner mitochondrial membrane, and the short soluble form (Dynamin-like GTPase MGM1, short form; S-MGM1), which results from proteolytic cleavage and localizes in the intermembrane space (By similarity). Both forms (L-MGM1 and S-MGM1) cooperate to catalyze the fusion of the mitochondrial inner membrane (By similarity). The equilibrium between L-MGM1 and S-MGM1 is essential: excess levels of S-MGM1, following loss of mitochondrial membrane potential, lead to an impaired equilibrium between L-MGM1 and S-MGM1, inhibiting mitochondrial fusion (By similarity). Plays a role in the maintenance and remodeling of mitochondrial cristae, some invaginations of the mitochondrial inner membrane that provide an increase in the surface area. Probably acts by forming helical filaments at the inside of inner membrane tubes with the shape and dimensions of crista junctions; [Dynamin-like GTPase MGM1, long form]: Constitutes the transmembrane long form (L-MGM1) that plays a central role in mitochondrial inner membrane fusion and cristae morphology (By similarity). L-MGM1 and the soluble short form (S-MGM1) form higher-order helical assemblies that coordinate the fusion of mitochondrial inner membranes (By similarity). Inner membrane-anchored L-MGM1 molecules initiate membrane remodeling by recruiting soluble S-MGM1 to rapidly polymerize into a flexible cylindrical scaffold encaging the mitochondrial inner membrane (By similarity). Once at the membrane surface, the formation of S-MGM1 helices induce bilayer curvature (By similarity). MGM1 dimerization through the paddle region, which inserts into cardiolipin-containing membrane, promotes GTP hydrolysis and the helical assembly of a flexible MGM1 lattice on the membrane, which drives membrane curvature and mitochondrial fusion; [Dynamin-like GTPase MGM1, small form]: Constitutes the soluble short form (S-MGM1) generated by cleavage by PCP1, which plays a central role in mitochondrial inner membrane fusion and cristae morphology (By similarity). The transmembrane long form (L-MGM1) and the S-MGM1 form higher-order helical assemblies that coordinate the fusion of mitochondrial inner membranes (By similarity). Inner membrane-anchored L-MGM1 molecules initiate membrane remodeling by recruiting soluble S-MGM1 to rapidly polymerize into a flexible cylindrical scaffold encaging the mitochondrial inner membrane (By similarity). Once at the membrane surface, the formation of S-MGM1 helices induce bilayer curvature (By similarity). MGM1 dimerization through the paddle region, which inserts into cardiolipin-containing membrane, promotes GTP hydrolysis and the helical assembly of a flexible MGM1 lattice on the membrane, which drives membrane curvature and mitochondrial fusion. Excess levels of S-MGM1 produced by cleavage by PCP1 following stress conditions that induce loss of mitochondrial membrane potential, lead to an impaired equilibrium between L-MGM1 and S-MGM1, thereby inhibiting mitochondrial fusion (By similarity).
Subcellular Localization:
[Dynamin-like GTPase MGM1, long form]: Mitochondrion inner membrane; Single-pass type II membrane protein; Intermembrane side; [Dynamin-like GTPase MGM1, small form]: Mitochondrion intermembrane space.
Domain:
The paddle region plays a major role in driving mitochondrial inner membrane fusion. It binds lipid membranes enriched in negatively charged phospholipids, such as cardiolipin, and promotes membrane tubulation. MGM1 dimerization through the paddle domain promotes the helical assembly of a flexible MGM1 lattice on the membrane, driving mitochondrial fusion in cells.
Sequence:
MSAQLRAAAAITPAARRVISGPAAVRRFHHYHHLPTGGIQRVEIAARGLRRSVQFPALANAYHNNAVIVRNASFTRLLPKLALKFIRVPALFGGMMLGAVGWVQYQAIKVSNSAQEFYGNIKATVADTAFSVWSSAVDIAEQTKRGWENTKNQFEIPEWLDRIMKGEGLAGEGSGSGEGGPNGGPEPPRQSRAGAATVAGASATVYGYGASDNDDRTPEEIMRDDNMMFITKKMIEIRNLLQKVGQGSTVTLPSIVVIGSQSSGKSSVLEAIVGHEFLPKGSNMITRRPIELTLVNDPEAKVDYGEFPDLGLARVTDFSLIQKTLTELNQSVPESECVTDDPIRLTIHSPNIPDLSLIDLPGYIQVAGENQPRELKRKITELCDKYIRGPNIILAISAADTDLANSTALQASRRVDPRGERTIGVITKMDLVEPEKGAAILSDRQYPLKLGYVGVISKLPPQSGLFRRDTGNLLASINRNEKNYFGSHPTEFGPDSGVSTGVMTLRKKLLQVLEQQMSSKLNETTEAIQRELEETTYQFKVQYNEQPMSAESYLAASLDDFKHQFHEFASSFGRPQLQTLLKDALDQKVLDQLAARYWNRPIEDLSPAPREPDNIIDLPKADPDSPYWHRQLDTACSGLTRLGVGRLAATVAASAIQQHVEKLLDKSSFAKHPSARKVISDAAATVLADRSYATSDGIEISLKPYKFDPDIQPNEWAQGREHVVGVLQAELEQCQAAMKALENSVGGRKKLKEVMSFVDKARKGEIIVEGDHPSGAGGFSAALLARGREAVFLRDRADILSLRIQAAKSRQCKTLTNKYYCPEVFLDAVATKLAQTAVLFLNVEMLNDFYVRFPREVEAKLHEHMHAGGGLEKFAREDPKVRRHLDLIRRKELLETVLGKIEELHRISSGTAGTLGLRGAGDLKKRIGAPSSSGRRSFF