Molecular cloning and analysis of SSc5D, a new member of the scavenger receptor cysteine-rich superfamily.
Glycoproteins of the scavenger receptor cysteine-rich (SRCR) superfamily contain one or more protein modules homologous to the membrane-distal domain of macrophage scavenger receptor I. These domains can be found in the extracellular regions of membrane proteins and in secreted glycoproteins, from the most primitive species to vertebrates. A systematic, bioinformatics-based search for putative human proteins related to the forty-seven known human group B SRCR domains identified a new family member that we have called Soluble Scavenger with 5 Domains (SSc5D). SSc5D is a new soluble protein whose expression is restricted to monocytes/macrophages and T-lymphocytes, and is particularly enriched in the placenta. The gene encoding SSc5D spans 30kb of genomic DNA, and contains fourteen exons producing a 4.8kb-long mRNA. The mature polypeptide is predicted to consist of 1573 amino acids comprising, towards the N-terminus, five very similar SRCR domains that are highly conserved among non-marsupial mammals, and a large (>250nm), very heavily glycosylated, mucin-like sequence towards the C-terminus. Each of the SRCR domains is encoded by a single exon, and contains eight cysteine residues, as observed for all other group B SRCR domains. A shorter isoform encoded by a weakly expressed, alternatively spliced transcript, which lacks the mucin-like C-terminal region, was also identified. It seems likely that SSc5D has a role at the interface between adaptive and innate immunity, or in placental function.
Gonçalves
Carine M
CM
Institute for Molecular and Cellular Biology, Porto, Portugal.
Castro
Mónica A A
MA
Henriques
Telmo
T
Oliveira
Marta I
MI
Pinheiro
Hugo C
HC
Oliveira
Carla
C
Sreenu
Vattipally B
VB
Evans
Edward J
EJ
Davis
Simon J
SJ
Moreira
Alexandra
A
Carmo
Alexandre M
AM
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002460:Cell Line; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D010802:Phylogeny; D010920:Placenta / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051122:Scavenger Receptors, Class B / Q000145:classification / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism
D020033:Protein Isoforms; D012333:RNA, Messenger; C543737:SSc5D protein, human; D051122:Scavenger Receptors, Class B