CASP-like protein 2A2 (PtCASPL2A2) is a small tetraspan membrane protein belonging to the CASP-like (CASPL) subfamily, the more divergent relatives of the bona fide Casparian strip membrane domain proteins (CASP1-5). Like other family members it has a central MARVEL-like four-transmembrane domain and is predicted to reside in the plasma membrane as a multi-pass protein. CASP-like proteins are not enzymes; by analogy with the characterized CASP scaffolds they are thought to organize plasma-membrane microdomains, but the specific biological role and tissue context of CASPL2A2 remain uncharacterized. The protein is predicted to form homodimers and heterodimers. In poplar, PtCASPL2A2 is leaf-enriched (~24 TPM) at baseline (EBI Expression Atlas E-GEOD-81077).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0005886
plasma membrane
|
IEA
GO_REF:0000044 |
ACCEPT |
Summary: CASPL2A2 is a multi-pass membrane protein of the CASP-like family; plasma membrane localization is the supported cellular component and the only well-grounded annotation for this otherwise uncharacterized protein.
Reason: UniProt reports cell membrane (plasma membrane) localization as a multi-pass membrane protein, consistent with the CASP/CASPL family and the four predicted transmembrane helices in the sequence record.
Supporting Evidence:
file:POPTR/CASPL2A2/CASPL2A2-uniprot.txt
SUBCELLULAR LOCATION: Cell membrane
file:POPTR/CASPL2A2/CASPL2A2-uniprot.txt
DR GO; GO:0005886; C:plasma membrane; IEA:UniProtKB-SubCell.
|
Q: In which tissues is PtCASPL2A2 expressed, and does it organize a distinct plasma-membrane microdomain like the bona fide CASP proteins or serve a different role?
Experiment: Determine the expression pattern and subcellular localization of tagged PtCASPL2A2 across poplar tissues to identify where it acts and whether it forms membrane microdomains.
Type: expression and localization profiling
id: B9GHX8
gene_symbol: CASPL2A2
product_type: PROTEIN
status: DRAFT
taxon:
id: NCBITaxon:3694
label: Populus trichocarpa
description: CASP-like protein 2A2 (PtCASPL2A2) is a small tetraspan membrane protein belonging to the
CASP-like (CASPL) subfamily, the more divergent relatives of the bona fide Casparian strip membrane
domain proteins (CASP1-5). Like other family members it has a central MARVEL-like four-transmembrane
domain and is predicted to reside in the plasma membrane as a multi-pass protein. CASP-like proteins
are not enzymes; by analogy with the characterized CASP scaffolds they are thought to organize plasma-membrane
microdomains, but the specific biological role and tissue context of CASPL2A2 remain uncharacterized.
The protein is predicted to form homodimers and heterodimers. In poplar, PtCASPL2A2 is leaf-enriched
(~24 TPM) at baseline (EBI Expression Atlas E-GEOD-81077).
existing_annotations:
- term:
id: GO:0005886
label: plasma membrane
evidence_type: IEA
original_reference_id: GO_REF:0000044
qualifier: located_in
review:
summary: CASPL2A2 is a multi-pass membrane protein of the CASP-like family; plasma membrane localization
is the supported cellular component and the only well-grounded annotation for this otherwise uncharacterized
protein.
action: ACCEPT
reason: UniProt reports cell membrane (plasma membrane) localization as a multi-pass membrane protein,
consistent with the CASP/CASPL family and the four predicted transmembrane helices in the sequence
record.
supported_by:
- reference_id: file:POPTR/CASPL2A2/CASPL2A2-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cell membrane'
- reference_id: file:POPTR/CASPL2A2/CASPL2A2-uniprot.txt
supporting_text: DR GO; GO:0005886; C:plasma membrane; IEA:UniProtKB-SubCell.
references:
- id: GO_REF:0000044
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping,
accompanied by conservative changes to GO terms applied by UniProt
findings:
- statement: GO_REF:0000044 supplied the plasma membrane GOA annotation reviewed in this file.
- id: file:POPTR/CASPL2A2/CASPL2A2-uniprot.txt
title: UniProtKB reviewed entry for CASPL2A2
findings:
- statement: UniProt identifies CASPL2A2 as a CASP-like protein of the Casparian strip membrane proteins
family, a multi-pass cell membrane protein.
- id: file:POPTR/CASPL2A2/CASPL2A2-goa.tsv
title: QuickGO GOA annotations for CASPL2A2
findings:
- statement: GOA supplied the plasma membrane annotation reviewed in this file.
- id: PMID:24920445
title: Functional and evolutionary analysis of the CASPARIAN STRIP MEMBRANE DOMAIN PROTEIN family.
findings:
- statement: Defines the CASP/CASPL family and distinguishes the divergent, largely uncharacterized
CASP-like subfamily from the bona fide Casparian strip CASP proteins.
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: PubMed-verified; family-defining paper that establishes the CASP/CASPL nomenclature
and the uncharacterized status of the CASP-like subfamily to which this protein belongs.
- id: file:projects/CASPL_FAMILY/bioinformatics/expression/RESULTS.md
title: Poplar CASPL expression analysis (EBI Expression Atlas) - RESULTS
findings:
- statement: PtCASPL2A2 is leaf-enriched at baseline.
core_functions:
- description: Predicted plasma-membrane CASP-like family protein of uncharacterized specific function,
inferred to act in organizing plasma-membrane microdomains.
supported_by:
- reference_id: file:POPTR/CASPL2A2/CASPL2A2-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cell membrane'
- reference_id: file:POPTR/CASPL2A2/CASPL2A2-uniprot.txt
supporting_text: Belongs to the Casparian strip membrane proteins (CASP)
locations:
- id: GO:0005886
label: plasma membrane
proposed_new_terms: []
suggested_questions:
- question: In which tissues is PtCASPL2A2 expressed, and does it organize a distinct plasma-membrane
microdomain like the bona fide CASP proteins or serve a different role?
suggested_experiments:
- description: Determine the expression pattern and subcellular localization of tagged PtCASPL2A2 across
poplar tissues to identify where it acts and whether it forms membrane microdomains.
experiment_type: expression and localization profiling