small ribosomal subunit protein uS2B; 37 kD laminin receptor; 37LRP; 37/67 kD laminin receptor; LRP/LR; 40S ribosomal protein SA; 40S ribosomal protein SA2; 67 kD laminin receptor; 67LR; laminin receptor 1; lamR; laminin-binding protein p40; LBP/p40 (RPSA2, RPSA, RPSAP58)
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Function
- required for the assembly &/or stability of the 40S ribosomal subunit
- required for the processing of the 20S rRNA-precursor to mature 18S rRNA in a late step of the maturation of 40S ribosomal subunits
- also functions as a cell surface receptor for laminin
- plays a role in cell adhesion to the basement membrane & in the consequent activation of signaling transduction pathways
- may play a role in cell fate determination & tissue morphogenesis
- also acts as a receptor for several other ligands, including the pathogenic prion protein, viruses, & bacteria
- acts as a PPP1R16B-dependent substrate of PPP1CA
- acylated. acylation may be a prerequisite for conversion of the monomeric 37 kD laminin receptor precursor (37LRP) to the mature dimeric 67 kD laminin receptor (67LR), & may provide a mechanism for membrane association
- cleaved by stromelysin-3 (ST3) at the cell surface
- cleavage by stromelysin-3 may be a mechanism to alter cell-extracellular matrix interactions
- interacts with RPS21
- interacts with several laminins including at least LAMB1
- interacts with MDK. the mature dimeric form interacts with PPP1R16B (via its fourth ankyrin repeat)
- interacts with PPP1CA only in the presence of PPP1R16B
- component of the small ribosomal subunit*
* mature ribosomes consist of a small (40S) & a large (60S) subunit
* the 40S subunit contains about 33 different proteins & 1 molecule of RNA (18S)
* the 60S subunit contains about 49 different proteins & 3 molecules of RNA (28S, 5.8S & 5S).
Structure
- monomer (37LRP) & homodimer (67LR).
- belongs to the universal ribosomal protein uS2 family
Compartment
- cell membrane cytoplasm . nucleus
- 67LR is found at the surface of the plasma membrane, with its C-terminal laminin-binding domain accessible to extracellular ligands
- 37LRP is found at the cell surface, in the cytoplasm & in the nucleus.
- co-localizes with PPP1R16B in the cell membrane
Comparative biology
- this protein appears to have acquired a second function as a laminin receptor specifically in the vertebrate lineage