AltMIEF1 / AltMiD51 / MIEF1-MP (UniProt L0R8F8) - review notes

Identity

70-aa product of an upstream ORF in exon 2 (5' leader) of the bicistronic MIEF1 gene, in a
different frame from MiD51/MIEF1 (Q9NQG6), the outer-membrane DRP1 fission adaptor. Folder
follows the <HOST>__<ACC> alt-ORF convention. The MIEF1 (MiD51) folder was not touched.
Abundance: [PMID:30181344 "levels of the 70 amino acid altMiD51, a small protein encoded in an exon originally annotated as \"non-coding\" of MIEF1/SMCR7L/MiD51 are two to six times higher than the levels of the canonical MiD51 protein in cells and in a human tissue"]
LYR-motif (Complex1_LYR, IPR008011 / PF05347) protein; three helices in the PDB structures.

Discovery by cryo-EM: PMID:28892042
LYR contact with mt-ACP 4-PP: PMID:28892042
Anti-association: PMID:28892042
Reproduced in GTPBP5 (PMID:34135318), GTPBP7/GTPBP10 (PMID:38042949) and MRM2 (PMID:35177605) intermediates: PMID:38042949
Loss of function: PMID:31666358 (abstract only; full text not retrievable)

PMID:30215512 Rescue with siRNA-resistant MIEF1-MP controls for MiD51 co-knockdown.
NDUFAB1 interaction is LYR-dependent but had no functional effect on complex I activity or lipid synthesis in that study.

Overexpression only: PMID:29083303 This is DRP1-dependent and LYR-dependent, with no loss-of-function data. Marked as an over-annotation.

The UniProt FUNCTION line cites PMID:31666358, but the abstract attributes the complex I N-module defect to LYRM2. The full text was unavailable, so this is UNDECIDED. Even if real, the defect is likely secondary to reduced ND-subunit translation.

ACCEPT: 3x mtLSU assembly, 2x mtLSU binding, 3x mitochondrion, 4x matrix
KEEP_AS_NON_CORE: positive regulation of mitochondrial translation
MARK_AS_OVER_ANNOTATED: mitochondrial fission
UNDECIDED: complex I assembly
MODIFY: protein binding with MRPL4 -> GO:0140978
REMOVE: protein binding with NDUFAB1 (x2), MALSU1, MRPS27
No GO term exists for LYRM binding of the ACP phosphopantetheine arm; no NEW terms proposed.