Cytoskeletal actin IIb

Function

CyIIb codes for cytoskeletal actin IIb. 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.

Protein

Cytoskeletal actin IIb
SWISS_PROT: P10991

Subcellular location

Cytoplasmic

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.
CyIIb message accumulation is transcriptionally regulated (Lee et al., 1992). The accumulation of zygotic origin transcripts of CyIIb is first observed at 12 hr after fertilization (Lee et al., 1992).
Specification of the founder cell populations for the cell type that will express cytoskeletal actin genes begins as early as 3rd cleavage and is compleated by the 64-cell stage (Cameron et al., 1987).
In situ hybridization (Cox et al.,1986) and lineage tracer studies suggest that all cells at the 64-cell stage activate CyIIb. CyIIb is initially globally expressed but ultimately is silenced in aboral ectoderm while continuing to be actively expressed in oral ectoderm and gut.

mRNA level

Temporal accumulation
Method 1: in vivo labeling
Reference: Lee et al., 1992
Method 2: molecular titration
Reference: Lee et al., 1986

Developmental time interval (hr) 8-20 20-36 36-65

Average number of cells expressing CyIIb gene 245 200 550

Amount of actin mRNA as measured by 1 (transcripts/embryo) 1,1 x 10^4 1,2 x 10^4 5,9 x 10^4

Amount of actin mRNA as measured by 2 (transcripts/embryo) 2,8 x 10^4 2,0 x 10^3 2,8 x 10^4

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

Stage 20 hr late gastrula pluteus

Tissue All cells The lineages destined to form oral ectoderm and gut Oral ectoderm, stomach, intestine

Sequences

GenBank:

complete cds

Regulatory Regions

Regions

Regulatory Connections

Upstream Genes

CyIIb

Downstream Genes

Evolutionary Homologues

CyI S.purpuratus
CyIIa S.purpuratus
CyIIIa S.purpuratus
CyIIIb S.purpuratus
M actin S.purpuratus
other actins

Links

Urchin Web

Bibliography

UrchiNet

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Developmental time interval (hr)	8-20	20-36	36-65
Average number of cells expressing CyIIb gene	245	200	550
Amount of actin mRNA as measured by 1 (transcripts/embryo)	1,1 x 10^4	1,2 x 10^4	5,9 x 10^4
Amount of actin mRNA as measured by 2 (transcripts/embryo)	2,8 x 10^4	2,0 x 10^3	2,8 x 10^4

Stage	20 hr	late gastrula	pluteus
Tissue	All cells	The lineages destined to form oral ectoderm and gut	Oral ectoderm, stomach, intestine