Peptide vs Steroid Hormones

Peptide Hormones

Steroid Hormones

Structure

Site of synthesis

Regulation of release

Transport in bloodstream

Specificity

Timing of effect

Mechanism of effect

hydrophillic, large or small (polypeptide or amino acid derivatives

rough ER

stored in vesicles until secretion signal recieved

free, dissolve into the plasma

target cells have appropriate receptors

second messenger cascade to effect enzyme actiivity

rapid, short lived

hydrophobic, small

smooth ER

synthesized when needed and used immediately

stuck to protein carrier (albumin)

target cells have appropriate receptors

Regulate DNA transcription to alter gene expression

slow, long lasting