CG32086 (synonym CG6100) encodes an uncharacterized Drosophila member of the EFHB (EF-hand domain-containing family member B, CFAP21) subfamily of the EFHC/EFHB protein family. M9NF85 is a 475-residue alternative isoform of the gene, identical to the 491-residue CG32086-RA product (Q8IQG0) except for a 16-residue internal deletion, and it retains the C-terminal EFHB-type EF-hand domain (residues 399-469). The fly protein lacks the canonical calcium-binding EF-hand loop present in vertebrate EFHB. The gene is expressed in elongating spermatids. Vertebrate EFHB proteins are microtubule inner proteins of ciliary and sperm flagellar doublet microtubules, and the fly protein is predicted by family membership to share that axonemal location, but no experimental study of CG32086 function, binding activity or localization has been reported.
Loading supporting content…
Download this section (compressed HTML)Q: Should the IBA calcium ion sensor activity (GO:0061891), regulation of store-operated calcium entry and regulation of calcineurin-NFAT signaling terms on the CG32086-RA product (Q8IQG0) stand, given that the fly EFHB-subfamily proteins lack the canonical calcium-binding loop and the donor evidence is a single human study?
Q: Does the 16-residue segment present in Q8IQG0 but absent from M9NF85 have any isoform-specific role, or are the two products functionally equivalent?
Experiment: Tag endogenous CG32086 and image elongating spermatids and mature sperm, and check for the protein in cryo-EM or proteomic analyses of fly sperm axonemal doublet microtubules.
Hypothesis: CG32086 is a microtubule inner protein of the sperm flagellar axoneme.
Type: localization
Experiment: Generate a CG32086 null allele, alone and combined with loss of the two EFHB-subfamily paralogs, and assay male fertility and sperm motility.
Hypothesis: The fly EFHB-subfamily proteins are redundantly required for sperm flagellar function.
Type: genetic loss of function
What is not known — curated, literature-grounded statements of the open unknowns (the inverse of core functions).
Gap: The molecular activity and cellular location of the CG32086 product are undetermined; whether it is a microtubule inner protein of Drosophila sperm flagellar doublet microtubules, as its vertebrate EFHB relatives are, whether its non-canonical EF-hand region binds any metal ion, what it binds, and whether loss of function has a phenotype (alone or with its two EFHB-subfamily paralogs FBgn0053489 and FBgn0053490) are all untested.
BIOLOGY WHOLLY_DARK
What is known: The gene is an EFHB-subfamily (PTHR12086:SF12) member expressed in elongating spermatids, and the encoded protein lacks a canonical calcium-binding EF-hand loop.
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)