SH3D21 (SH3 domain‑containing protein 21) is a protein‑coding gene found in the human genome. The gene encodes a protein that possesses one or more Src homology 3 (SH3) domains, which are small protein‑interaction modules commonly involved in signal transduction and cytoskeletal organization.
Genomic location
According to publicly available genome annotations (e.g., NCBI Gene, Ensembl), the SH3D21 locus is situated on chromosome 5 in the human genome. Precise cytogenetic band assignments may differ among annotation releases.
Gene and protein structure
- Gene ID: The gene is assigned a stable identifier in major databases (e.g., NCBI Gene ID 84944).
- Transcript variants: Multiple transcript isoforms have been reported, arising from alternative splicing.
- Protein length: The primary isoform encodes a polypeptide of several hundred amino acids (exact length varies with isoform).
- Domain architecture: The protein contains at least one SH3 domain, a ~60‑residue β‑barrel motif that mediates binding to proline‑rich sequence motifs in partner proteins.
Expression profile
Expression data derived from high‑throughput RNA sequencing projects indicate that SH3D21 is transcribed at low to moderate levels in a variety of human tissues, with comparatively higher expression reported in certain brain regions and lymphoid tissues.
Biological function
The precise cellular role of SH3D21 remains incompletely characterized. By virtue of its SH3 domain(s), the protein is presumed to participate in protein‑protein interaction networks that modulate signaling pathways, possibly related to cytoskeletal dynamics or vesicular trafficking. Experimental studies have not yet defined definitive molecular functions or physiological processes in which SH3D21 is essential.
Clinical relevance
No definitive associations between genetic variants in SH3D21 and specific human diseases have been established in peer‑reviewed literature. The gene is occasionally listed among candidate loci in genome‑wide association studies, but functional validation is lacking.
Research tools
- Antibodies: Commercially available polyclonal and monoclonal antibodies target epitopes within the SH3D21 protein.
- Knock‑down/knock‑out models: Small interfering RNA (siRNA) and CRISPR‑Cas9 reagents targeting SH3D21 have been employed in cell‑based studies to investigate phenotypic consequences of reduced expression.
References
- NCBI Gene: “SH3D21 SH3 domain containing 21 (human)” (accessed 2026).
- UniProtKB entry Q8TCT0 – “SH3D21_HUMAN”.
- Ensembl release 112 – gene summary for SH3D21 (GRCh38).
Note: While the existence of the SH3D21 gene and its basic molecular features are well documented, detailed functional and clinical information remains limited.