he LRP5 cDNA encodes a deduced
1,615-amino acid protein containing conserved modules characteristic of the LDLR family, including a putative signal
peptide, 4 epidermal growth factor (EGF) repeats with associated spacer domains, 3 LDLR repeats, a single
transmembrane-spanning domain, and a cytoplasmic domain. The extracellular domain of LRP5 contains 6 potential
N-linked glycosylation sites. Of the known family members, LRP5 is most closely related to LRP1 (OMIM 107770).
However, LRP5 has a unique organization of EGF and LDLR repeats compared to other LDLR family members and
likely represents a new category in this family.
General function
Receptor
Comment
Cellular localization
Plasma membrane
Comment
Ovarian function
Comment
Expression regulated by
Comment
Ovarian localization
Oocyte
Comment
Taft RA, et al 2002 reported the identification of genes encoding mouse oocyte secretory and
transmembrane proteins by a signal sequence trap.
At all stages of follicular
development, oocytes interact with surrounding granulosa cells and promote their
differentiation into the types of cells that support further oocyte growth and
developmental competence. These interactions suggest the existence of an
oocyte-granulosa cell regulatory loop that includes both secreted proteins and cell
surface receptors on both cell types. Factors involved in the regulatory loop will
therefore contain a signal sequence, which can be used to identify them through a
signal sequence trap (SST). A screen of an oocyte SST library identified three
classes of oocyte-expressed sequences: known mouse genes, sequences homologous
to known mammalian genes, and novel sequences of unknown function. Many of the
recovered genes may have roles in the oocyte-granulosa cell regulatory loop. For
several of the known mouse genes, new roles in follicular development are implied
by identification of their expression, for the first time, in the oocyte.
LRP5 was found by the SST screen.