Table 8 Human hsp70 genes: Expression modality and location of their proteins
Gene | Cell locale | Tissue | Modality of expression |
|---|---|---|---|
HSPA8 | Cytosol. Translocate to nucleus and nucleoli upon heat shock. Surface of embryonic stem cells | Highly expressed in all tisuses | Constitutive. Moderately induced by heat shock |
HSPA2 | Nucleus | Mostly in testis, skeletal and heart muscles, esophagous, brain | Constitutive |
HSPA1A and HSPA1B | Cytosol. Nucleus and nucleoli upon heat shock | All tissues | Strongly induced by heat shock |
HSPA1L | Mostly cytosol under basal conditions. Nucleus but not nucleoli upon heat shock | Spermatides | Constitutive. Not induced by heat shock |
HSPA6 | Cytosol. Nucleus | Most tissues | Induced by heat shock. No basal expression |
HSPA5 | Endoplasmic reticulum (ER) | All tissue | Induced by ER stressors |
HSPA9B | Mitochondria. ER. Cytosol. Cytosolic vesicles. Membrane surface | Many tissues | Constitutive |
STCH | Microsomas | All tissues | Constitutive |
HSPA14 | Cytosol. Associated to ribosomes | Many tissues (low expression) | Undetermined |
HSPA4 | Cytosolic (?) | Most tissues | Constitutive. Not induced by heat shock |
HSPA4L | Cytosol. Nucleus upon heat shock | Mostly testis | Constitutive. Induced by heat shock in somatic cells but not in germ cells |
HSPH1 | Cytosol. Nucleus upon heat shock, possibly nucleoli | Most tissues | Constitutive. Induced by heat shock |
HYOU1 | ER. Cytosol (isoform 3) | Liver, pancreas. Highly expressed in cells with well developed ER | Induced by ER stressors |
HSPA12A | Undetermined yet | Brain. Kidney. Muscle | Constitutive. Induced by stress |
HSPA12B | Undetermined yet | Skeletal and heart muscles | Constitutive. Induced by stress |