SCAVENGER RECEPTOR CYSTEINE-RICH FAMILY MEMBER WITH 4 DOMAINS; SSC4D

Alternative titles; symbols

• PROTEIN WITH 4 GROUP B SCAVENGER RECEPTOR CYSTEINE-RICH DOMAINS; SRCRB4D
• S4D-SRCRB

HGNC Approved Gene Symbol: SSC4D

Cytogenetic location: 7q11.23 Genomic coordinates (GRCh38): 7:76,389,336-76,410,024 (from NCBI)

▼ Description
The scavenger receptor cysteine-rich (SRCR) superfamily is an ancient and highly conserved group of cell surface and/or secreted proteins, some of which are involved in the development of the immune system and the regulation of both innate and adaptive immune responses. Group B SRCR domains usually contain 8 regularly spaced cysteines that give rise to a well-defined intradomain disulfide-bond pattern.

▼ Cloning and Expression
By screening EST databases for proteins similar to CD5 (153340) and/or CD6 (186720), followed by 5-prime RACE of a stomach cDNA library, Padilla et al. (2002) obtained a full-length cDNA encoding SRCRB4D. The deduced full-length protein contains 575 amino acids. Use of an alternate translation initiation codon predicts a 569-amino acid protein containing a putative hydrophobic signal sequence and a peptidase cleavage site, resulting in a mature protein of 528 amino acids with a calculated molecular mass of about 55.6 kD. SRCRB4D contains 4 group B SRCR domains of 101 amino acids separated by PST-rich regions. SRCRB4D has no N-glycosylation site or transmembrane region. Northern blot analysis detected a 2.8-kb transcript expressed mainly in kidney and placenta and a 1.5-kb transcript with a more widespread distribution. A similar mRNA expression pattern was found in several tumor cell lines.

▼ Gene Structure
Padilla et al. (2002) determined that the SRCRB4D gene contains at least 11 exons and spans more than 20 kb.

▼ Mapping
By genomic sequence analysis and radiation hybrid analysis, Padilla et al. (2002) mapped the SRCRB4D gene to chromosome 7q11.23, telomeric to the Williams-Beuren syndrome (194050) deletion region and oriented tail-to-head relative to the centromere. Southern blot analysis determined that SRCRB4D is a single-copy gene.