Strongylocentrotus purpuratus Genes in Development:
Proteases
SuBMP
Function
SuBMP codes for a protein which belongs to the family of
huBMP-1 related proteins.
SuBMP may be involved in events leading to biomineralization
(spiculogenesis) (Hwang et al., 1994)
Protein
SuBMP protein contains a signal peptide at its
N-termini, followed by an activation region, protease (P) domain,
a C1r/C1s domain, an imperfect repeat of C1r/C1s domain and an EGF-like domain.
The P domain,
containing 193 amino acids near the N-terminal
region, exhibits 36 % sequence identity with
that of the astacin metalloprotease. In this domain suBMP
contains the active site consensus sequence
typical of metalloendoproteases, namely,
HEXXH.
The C1r/C1s domain of SuBMP, containing 100 amino acids
near the C-terminal region, exhibits 27 % sequence
identity with domain I of human C1r and C1s serine
proteases in the complement cascade. This domain
also shares sequence homology with the C-terminal
region of the calcium-dependent serine protease precursor.
The IR domain, containing 120 amino acids, is an imperfect
repeat of the C1r/C1s domain. The E domain contains a segment
of 45 amino acids that shares 42 % sequence identity
with human epidermal growth factor (EGF) precursor.
This region contains 6 cysteine residues spaced between
other conserved residues in the sequence
DXCX7CX3CXNX4YXCXCX4EX7C. This spacing of cysteine residues is the
same as that found in human EGF precursor, except that
in EGF the segment between the first two cysteine
residues contains 6 instead of 7 residues (Hwang et al., 1994).
Several, if not all, of the four potential
N-linked glycosylation sites in
suBMP are glycosylated (Hwang et al., 1994).
SWISS_PROT: P98069
Subcellular location
The immunoelectron microscopy revealed that suBMP was
present in the cytoplasm and on the surface of
ectodermal, endodermal (gut) and primary mesenchyme
(PM) cells. Clusters of SuBMP-antibody complex
were also seen on the surface of the cells and
within the blastocoel. In this extracellular
compartment SuBMP was detected on the surface
of filopodia of the PM cells, as well as on
elements of the extracellular matrix (Hwang et al., 1994).
Expression Pattern
Although SuBMP mRNA was detectable at a low level
in the unfertilized egg, maximal expression of mRNA
was observed at hatched blastula stage, with only a
modest decrease in level at later stages of development.
In situ hybridization studies revealed that suBMP
mRNA is found in both ectodermal and PM cells in
hatched blastula-stage embryos. Maximal expression of
suBMP was observed at hatched blastula stage.
A slight decrease in level was observed from mesenchyme blastula
to the 72 hour pluteus stage embryo.
A trace level of the protein was found in the
unfertilized egg, but not again detected until the blastula
stage. The highest level was observed at the mesenchyme blastula
stage; a slight decrease in SuBMP was observed at later stages.
Apparently, translation of the low level
of SuBMP mRNA in the unfertilized egg is repressed because the
ratio of expressed protein to mRNA is very low at this stage.
(Hwang et al., 1994).
mRNA level
Temporal accumulation
Method: Northern blot analysis
Reference: Hwang et al., 1994
Stage
Egg
Prehatching blastula
Hatched blastula
Mesenchyme blastula
Gastrula
Prism
Pluteus
Level
+
+
+
+
+
+
+
Protein level
Temporal accumulation
Method: Western blot analysis
Reference: Hwang et al., 1994
Gene Networks Database![[Previous]](arrow-1.gif){kind=icon}
UrchiNet![[Up]](arrow-3.gif){kind=icon}
Search the GeNet