calcium pump. the mechanism of active transport of calcium (Ca 2+) across a membrane, as of the sarcoplasmic reticulum of muscle cells, against a concentration gradient; the mechanism is driven by hydrolysis of ATP.
A rental agreement differs from a lease agreement in that it is not a long-term contract and usually occurs on a month-to-month basis. This month-to-month lease agreement expires and then renews each month upon agreement of the parties involved.
A lease or rental agreement sets out the rules landlords and tenants agree to follow in their rental relationship. It is a legal contract, as well as an immensely practical document full of crucial business details, such as how long the tenant can occupy the property and the amount of rent due each month.