MS4A3 MS4A3 (membrane-spanning 4-domains, subfamily A, membrane 3, CD20L, HTM4 (hematopoietic cell 4-transmembrane protein.
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 3 glycoprotein, 4 span
Hematopoietic Cell
Nonlymphoid tissue

Expression
MS4A3 is expressed in hematopoietic cells and tissues and nonlymphoid tissues.

Northern blot and reverse transcriptase-PCR analyses suggest that HTm4 mRNA expression is restricted to cells of hematopoietic origin.

Structure

MOLECULAR FAMILY NAME: Belongs to the membrane spanning 4A family.

MS4A3 is a single-pass type-3, 4 span 250 glycoprotein.  It contains an N-terminal extracellular domain, 4 highly conserved transmembrane domains and a C-terminal cytoplasmic domain.

HTm4 is a single chain type 3, 4 span glycoprotein.  It is a member of the CD20/FceRIb superfamily of leukocyte surface antigens which includes CD20 and the b subunit of the high affinity receptor for IgE FceRIb. These molecules are predicted to have 4 transmembrane regions, cytoplasmic N- and C-termini, and short extracellular loops.  The gene for HTm4 maps to the same region of the genome as CD20 and FceRIb.  The CD20/FceRIbsuperfamily shares no sequence similarity with members of the TM4SF which also have 4 transmembrane regions.

MOLECULAR MASS

POST-TRANSCRIPTIONAL MODIFICATION

Alternative splicing yields 2 different isoforms.

POST-TRANSLATIONAL MODIFICATION: No information.



Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH MS4A3: No information.

Function

Members of the membrane-spanning 4A family are characterized by common structural features and similar intron/exon boundaries display unique expression patterns among hematopoietic cells and nonlymphoid tissues.  MS4A3 likely plays a role in signal transduction and may function as a subunit associated with receptor complexes.  MS4A3 is a hematopoietic modulator for the G1-S cell cycle transition.  It modulates the level of phosphorylation of cyclin-dependent kinase 2 (CDK2) through its direct binding to cyclin-dependent kinase inhibitor 3 (CDKN3/KAP).  The C-terminal cytoplasmic domain is required for binding to CDKN3-CDK2 complexes and the modulation of CDKN3 activity.

HTm4 cDNA was identified as a marker of hematopoietic cells by subtractive hybridization screening of cDNA libraries.  The function of HTm4 is not known, although the sequence similarity to CD20 and FceRIb would suggest a role in signal transduction and/or as a subunit of receptor complexes. 

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF MS4A3 IN INTACT ANIMAL: No information.



Comments
MOLECULAR INTERACTION-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF MS4A3: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY MS4A3: No information.



Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 932Q96HJ5
Antibodies

Revised June 25, 2008


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