Gene Networks Database

Strongylocentrotus purpuratus Genes in Development: Cell type specific genes; Actins

Cytoskeletal actin IIIb


The CyIIIb actin gene codes for a cytoskeletal type actin (Flutzanis et al., 1989). Actin represents one of the most abundunt and best characterized structural components in eucaryotic cells, involved in a wide variety of cytoskeletal, locomotive, and tension-generating functions. Five functional cytoskeletal actin genes are organized in two linkage groups within the genome: CyI-CyIIa-CyIIb and CyIIIa-CyIIIb.


CyIIIb protein belongs to a family of the cytoskeletal actins (Flutzanis et al., 1989). CyIIIb sequence differs significantly (approx.50%) from the sequences of other sea urchin cytoskeletal actin proteins within an amino acid region from position 257 to 267.

Subcellular location


Expression Pattern

Developmental studies of actin mRNA prevalence have been caried out using several sensitive methods including in situ hybridization (Cox et al., 1986), molecular titration with single-strand RNA probes (Lee et al., 1986), RNA gel blot hybridization, and cDNA analysis (Shott et al., 1984; Crain et al., 1981; Garcia et al., 1984).
All of the S. purpuratus cytoskeletal actin genes are activated at 8-9 hr of development, a time when 64-128 cell embryos are predominant in large cultures.
CyIIIb message accumulation is transcriptionally regulated (Lee et al., 1992). CyIIIb mRNA accumulation is first observed at 10 hr postfertilization. Considerable amounts of mRNA do not accumulate until well into the pluteus stage 3 days later.
The CyIIIb actin gene is exclusively expressed in the aboral ectoderm by a combinatorial repression in all other cell lineages of the developing embryo (Flytzanis et al., 1989).

mRNA level

Spatial localization

Method: in situ hybridization
Reference: Cox et al., 1986

Stage 20 hr late gastrula pluteus
Tissue Aboral ectoderm Aboral ectoderm Aboral ectoderm



Regulatory Regions

Upstream regulatory region

Regulatory Connections

Upstream Genes



Downstream Genes

Evolutionary homologues


Urchin Web


[Previous]UrchiNet[Up] Search the GeNet
Comments are welcome to Kate G. Savostyanova
Copyright © 1997 GeNet Team