GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

UniProt SUBCELLULAR LOCATION annotation for CAHS3 (J7M3T1) records cytoplasmic localization with experimental evidence from PMID:22937162. This mapping reference is used to convert the controlled-vocabulary subcellular location into the GO:0005737 (cytoplasm) annotation with IEA evidence.

PMID:22937162

Two novel heat-soluble protein families abundantly expressed in an anhydrobiotic tardigrade

CAHS proteins identified by mass spectrometry from heat-soluble fraction
Cytoplasmic localization confirmed by immunofluorescence
Proposed involvement in anhydrobiosis

PMID:27649274

Extremotolerant tardigrade genome and improved radiotolerance of human cultured cells by tardigrade-unique protein

R. varieornatus genome contains 16 CAHS family members
CAHS genes are constitutively and abundantly expressed
No significant transcriptional changes during dehydration/rehydration
CAHS proteins proposed to protect biomolecules during desiccation

PMID:33545053

Reconsidering the glass transition hypothesis of intrinsically unstructured CAHS proteins in desiccation tolerance of tardigrades

Glass transition hypothesis for CAHS proteins reconsidered
Protection may occur via stabilization of vitrifying small molecules such as sugars
Direct glass transition of CAHS proteins themselves is unlikely the mechanism

file:RAMVA/CAHS3/CAHS3-deep-research-falcon.md

Deep research synthesis on CAHS3 (J7M3T1) from R. varieornatus

CAHS3 reversibly polymerizes into cytoskeleton-like filaments and undergoes a sol-gel transition under hyperosmotic / desolvating conditions; gelation in vitro occurs near ~4 mg/mL with high salt or TFE, and is abolished by structure-disrupting mutations such as CAHS3-L207P, linking filament formation to mechanical stiffening of the cytoplasm.
The C-terminal conserved regions CR1 and CR2 (helical/coiled-coil) are essential and sufficient for filament/gel formation, and CAHS3 expression in heterologous cells increases cell stiffness and improves resistance to hyperosmotic shrinkage, consistent with a mechanical-stabilizer role for the cytoplasm during dehydration.
CAHS3 is preferentially expressed in epidermal tissue in vivo and shares a ~300-350 bp upstream regulatory region (containing motifs MRv-6, MRv-7 and MRv-39) with several other CAHS paralogs, suggesting shared cis-regulatory logic for the CAHS family in R. varieornatus.